Okay, we have 10 times as many questions as we're going to get to it. I want you guys to be aware of that from the beginning. But the good news is, this is day one. None of these guys are going anywhere. So hunt them down over the next few days, and we'll try to get everything answered as we can. All right, let's get started. Define market timing. I reduced my bond duration prior to the Federal Open Market Committee raising rates. Is that market timing? Should I buy long bonds now and wait for rates to go down? If market timing doesn't work, how does prime cap and capital opportunity beat the market? Anyone want to volunteer for that one? Yes, that is market timing. And this is one of the problems that we all, most of us don't believe in market timing, but we use it. And that's a hard one because market timing can be systematic by some sort of a following a trend, following line of some sort, or it can be what we call the ICSIA market timing system. I can't stand it anymore. And the moment it becomes an emotional decision, remembering there's always a pile of good news about any trade and a pile of bad news. And so as a market timer, you're fighting trying to figure out which is more powerful. So I'm not an advocate of it, although half of my portfolio is market timing. You're going to have an allocation between stocks, bonds, cash, real estate, and you're going to stick with that. And if you're supposed to rebalance, you rebalance. And if you deviate from that, because you see something out there in the economy or interest rates of the Fed or China or Middle East or whatever, and you're going to make these decisions saying, I don't like what I see out there. I'm going to change my asset allocation in some way. That's market timing. Okay, let's do the next question. We're going to do this one rapid fire. We're going to go across the stage. We'll start with me and go across. Here's the question. If you've got a kid with a Roth IRA, should they be putting it in a target retirement fund or a total stock market index fund? Yeah, so generally Roth money from what I've seen is the last money that anybody ever spends. It generally goes to the kids because it goes to them tax free. And they have 10 years of which to distribute the money, tax free. So it's generally 100% equity. This may sound like a commercial. One of those three free books, two of those three free books, are focused on target date funds. And what we do recommend is you look at the implications of a target date fund and 10% small capital value. I believe the premium is actually going to happen. It's not a bad idea. I would say all stock portfolio because it's probably going to be an addendum to their own retirement account, which is probably in the target date fund anyway. I'm pretty much agreeing. The whole issue of asset location would suggest that with the Roth, that would be where the stocks and the small cap value if you're going to have it would be best positioned. Is mine on? Nothing different here. Total stock market index. You said it was for the child, right? Like an 18 year old. Yeah, absolutely. I'd go 100% stocks. I'm the different voice up here, apparently. My kids are in target retirement funds. I'll tell you the reason why. I'll tell you the reason why. I'm managing about 50 investment accounts. Between 34, 529s for nieces and nephews between our own retirement accounts, between my kids, we each have three accounts. It's a lot of accounts. So I'm looking for simple solutions.  And when they inherit it, they will have a simple solution. If they forget about it for 20 years, it's fine. They've got US stocks, they got international stocks, they got a very tiny amount of bonds. You really think total stock market is going to dramatically outperform a portfolio that's 90% stocks? No, probably not. So that's why I chose it. It's one of those questions. Probably doesn't matter that much, to be honest. Okay, next question. This one's from Mary Beth Franklin. Is there a reason one of us should not wait until presumably 70 to 60% of the total stock market is going to have sex social security benefits? I agree for married couples that splitting the difference you're hedging your bets. Have the one with the bigger benefit wait until 70, have the other spouse, if he or she's not working, claim early at 62, bring cash into the household. If they are working and subject to earnings restrictions, wait until full retirement age. Okay, here's a more controversial question. What's the amount of cash or cash equivalent when recommendations are all over the map? Well, you do want to have some sort of liquid contingency fund, and whether that's cash or whether that's some other buffer asset, something, it's hard to give a specific recommendation. Usually here like six months, something along those lines, I can't really get any more specific than that. You definitely do need something. I'm going to say the amount that lets you sleep at night. And so I've seen those numbers be all over the place for high income spenders. I've seen people that need to have $200,000 in cash set on the side. It's just what makes them feel comfortable. And people that are comfortable with 10,000 as long as they have their defined paycheck coming in. My wife and I, at the first of each year, we take out 5% of the whatever we have for retirement. And that's our money for the year. But on the other hand, the retirement, the buy and hold part is 50% bonds and 50% stocks. And a lot of the bonds are short term. So they aren't cash, but they are the same as cash. And so I think that you should, when you can, keep that cash working at something better than the return for cash. Yeah. So there's a difference between philosophy and strategy, right? Philosophy, we're all bogal heads. We all believe you have some sort of a emergency fund. I don't like to call it an emergency fund.  So how much should you have? This is strategy, which means strategy is individual. I don't know how much you should have.  What's your situation? How much cash do you need?  I mean, a hundred different things. Are you covered or your expenses covered by social security and maybe a pension of some sort? Do you need to have a lot of cash? Or maybe, you know, you want to spend a lot of cash. So strategy is individual. And how much you have in a reserve fund when you're retired is really an individual decision. I don't think there's any rule of thumb that can cover that. I like the idea of years. Because if you have a year like 2022 and stocks and bonds are down, well, you withdraw from the cash. So I like the idea of having two or three years worth. But there's obviously a cash drag to that. All right. Next question. Cyber security. Any quick questions to reduce the risk of financial accounts being compromised by cyber criminals, i.e. multifactor authentication, diversifying among multiple companies or accounts, et cetera? I'll tackle that one because we have to deal with those regulations. I mean, anything that has multifactor, I would turn it on. So, you know, if you can have where it sends a text message and you have to put that code in, or, you know, a Google Authenticator app that you can add to the account. So you have to put a six-digit code in every time you log in. I think that's the most effective thing. And really educating yourself on what not to click on. And so we had an employee for a while who would click on... I mean, he could fall for every email that came in that you shouldn't click on.  You would never put your account number in from a link that you would click on in an email. You would always go directly to that website to log in. So educating yourself is one of the biggest ways you can prevent those things from happening. Is it okay to have all your money at Vanguard? Say yes. Anybody disagree with that? All right, next question. Let's start with you on this, Wade. And if anybody else wants to weigh in, they can. How do you balance conversions from your IRA to your Roth account with Medicare increasing due to tax increase from additional income in that year? That question probably came in before the session. But indeed, you definitely want to be paying attention to those ERMA brackets. And then I didn't really get a chance to elaborate on the assumptions. I was basing it on this year's ERMA brackets, even though the tax won't come until two years later. But the issue is you don't know what those brackets will be two years later. So I treat it as a conservative assumption that if I stay under this year's brackets and then there's a little bit spare capacity where if the last day of the year markets went up and then my RMD is a little bit higher than expected, I still hopefully the brackets will be higher two years later. But I try to manage based on this year's brackets. If you don't want to go over that bracket, make sure you're not getting too close and pay attention. If you're in the RMD phase, pay attention at the end of the year because you don't know what your RMD is going to be for the next year until December 31st. The market closes. I would also agree with that because you know the ERMA brackets are now going to go up every year. So if you use the current ones, you're going to be on the safe side and you'll have a little more wakeover. Pass that down to Rick. He's got a comment on this. I'm just going to give a shout out to Stephen Chin if you're here and newretirement.com. Good software. Good software for helping figure this stuff out. It does it very inexpensive. You just sign up for a subscription. It's really good to help you. It gives you data points, gives you more information. So just a shout out to Steve. Got a good job on that and newretirement.com. This is Franklin. This one's for you probably. This is kind of the counter argument to wait till 70. Are social security benefits payments actuarially adjusted? Is there really a benefit to waiting until 70? Well, social security benefits are actually fair if you live to average life expectancy. And you do get this bonus of these delayed retirement credits of 8% a year. Back before the social security reforms, those delayed retirement credits were 3% a year. No one in their right mind delayed going to 70 because at the time interest rates were 18%. So when they came up with the concept of, hey, let's make the delayed retirement credits gradually increase to 8% a year. It's a huge bonus. If you can afford to wait, it really is worth it. I just added that to those actuarial calculations were done in 1983 and people are living longer now. And also with the high earner where that benefit will last for the joint lifetime of the couple. That's a different calculation. The actuarial calculations from social security were based on single people. Next one's a question for me. How much in rental properties is too much as a percentage of net worth? I think a reasonable amount of money to have in real estate is zero at 80%. So it's a very wide range. If you're more than 80, I think that's too much. And the second part of the question is, can real estate risk be diversified away by buying properties in multiple regions? You can diversify away some of your risk by doing that, but certainly not all of your real estate risk. All the real estate in the country and in the world can tank at the same time. All right, this one's for Wade Fow. How can I make a tax map? Well, it can be done in Excel spreadsheets. The preferential income part isn't too rough. The Irma brackets are pretty straightforward. You're going to have to spend the most time getting those social security tax torpedoes under control because it is a multi-step calculation. But you can ultimately do that in Excel where you're just looking at, okay, here's the ordinary income column and then you have to keep track, not just the federal income tax brackets, but when the Irma surcharges happen, the stacking of preferential income on top of that. And the hardest part for sure, the social security, the percent of your social security benefits that would be taxed. There is software you can use that advisors subscribe to. I don't see why you couldn't subscribe to it either. We use Holista Plan. There's also another one by Covissium. And so they're, you know, just don't know what, if it's going to be cost effective, but you can run your own tax projections and Holista Plan does an outstanding tax map. And the tax map idea, yeah, Covissium, that's the one that what I'm doing is the most similar to. Okay, we're going to do about two more questions here because I know we're just slightly over time. This one, how is social security claiming strategy affected by possible future insolvency of the trust fund? Let's just do a show of hands on this one. How many people on stage think that there will be no social security payments being made in 10 or 15 years? Okay, I think that answers that question. How about how many people on the stage think that the benefits may be a little bit lower than what people were expecting? Depending on the generation. All right, and let's do this one here. Can I just say something really quickly? Sure. We can only act under current law. We don't know what Congress is going to do. If you need the money, grab it early, and you know it's going to be reduced. But if you were taking a benefit early out of fear of what might happen 10 years from now, that is like selling your stocks in a down market. And we all know that no one in this room caches out when the market goes down. All you do is guarantee that you have locked in a loss. Okay, and we're going to end on this one. If I can read it here. Is this the time for a around 70-ish-year-old couple getting Social Security at 7 to consider seriously buying a deferred income annuity with our bond funds? Yeah, I want to get back to philosophy, strategy, discipline, the three key things that make you successful. The Boglehead's philosophy is not against annuities. Whether it works for you in your strategy or not is really unique to your situation. So I actually can't answer that question unless I knew the whole situation. All right, Dana? We use something we call a coverage ratio. So we look at how much of your cash flow is covered by guaranteed sources of income already. And if that's under 50%, it's when we bring up a discussion around do you want additional guaranteed income? Is that important to you? And so that could be one metric that you could look at. I completely agree with what Rick said, right? It's so personal. The other issue is cognitive decline. So we have seen strange things. Once we had the spouse of a client who was ordering things off of QVC and burying them in her backyard. And it took the husband months to figure out where it was like $3,000 to $4,000 a month, months to figure out where was this extra money going. And so, you know, a deferred income annuity could protect you against yourself. And I know that sounds like a strange thing to say, but it is absolutely guaranteed. And if the older you was prone to falling for investment fraud or making some strange decisions, it does offer some additional protection. And I don't hear that talked about all that often. And as a preview for tomorrow, Jim and I will have a session together where we'll be able to unpack that somewhere too. Yeah, for sure. Annuities can be very useful, particularly those that barely have enough or almost have enough. That can be a great way to fill that gap. All right. Well, this has been Boglehead's University. This is not supposed to be part of the conference, even though you all showed up a day early and came to it. So thank you for your attendance. Thank you to these wonderful people who out of the goodness of their heart came out here for the most part at their own expense. Most of us are paying our own conference fee as well, just like you are, and are just here out of the goodness of our hearts to share this information with you. Thank you to you guys. That's been wonderful. Thanks to everyone for coming. The party starts at five. It's in the room next door. It's cocktail hour. That's the traditional start to the Boglehead's conference, but it's been wonderful to share the afternoon with you, and thank you everyone for showing up early.


Today we're going to be continuing looking at applications that I use on my Android device and today We're looking at a black screen and a keyboard. That's right. It's the shell. I use now There are a few terminal applications out there for Android the one I use is more than just a terminal application It's term ux if you haven't heard about it check it out It's in both the Google Play Store and Fdroid and once you install it it not only gives you access a lot of the terminals out there you get for Android Access to the Android shell. This is different. It's actually a whole new environment And it has a package manager with a bunch of applications available in the repositories Now it's not quite a true, but it's pretty darn close now You don't need to root your phone for this but it gives you access to a lot of the tools You would have on a standard Linux system things like you know full version of Python It will give you like I use Axle to download stuff or I'm gonna talk more about other applications. I use an n-map Full busy box full bash session. I actually have Z shell installed on here with Tmux not term mux but Tmux for splitting the window and have multiple sessions going I have FM peg installed on here I'm gonna talk about later on but a lot of the core tools I use more than core tools a lot of tools I use are in the package manager in their repositories there and Now to explain this between this and a chair roots first of all chair root You're going to need to root your device You don't need to root your device to use term mux and you're still gonna have a lot of those applications now You'll still would need root if you want to do root stuff like accessing certain types of a hardware and stuff like that There's still gonna be restriction on that because Android just locks everything down that way Which is one of the in my opinion biggest drawbacks of Android, but But term mux just gives you 99% of what you're going to be doing Right there in package. So again a chair root. What a chair root is Basically, you'll have a Folder or a partition or an image that you have mounted that has a full Linux file system on it such as Debian for example and when you chair root into it Basically, you're telling the computer continue using the Linux kernel that we're currently using which is great because it has all your needed drivers loaded but For all the applications and everything we're going to do once we answer the chair root use this file system So everything but the kernel would be Debian and it's just like running Debian anywhere else Or whatever distribution using Term mux is a little different. I don't know the exact details on how it works But basically from my understanding when I read about it a while ago one of the things about difference between different Linux distributions is where files are stored and when you install an application. That's a binary application It is most likely dynamically linked. So it's going to look for libraries in certain folders. Well Term mux has variable set for different things So basically it's a very much like a chair root where it has its own folder where it stores all its stuff But instead of saying this is the root directory for everything just use the kernel It's just saying okay, we're gonna load up our shell We're gonna set these variables to look for certain things in certain places So it's very much like a chair root in that way, but you still have access. You're still in the The the Android operating system and can still access things that way once you get permission Which we'll talk about more once we get into the next video where I talk more about this But you're actually able to access and interact with Android with it as well, which is awesome if you want to be able to trade off your clipboard information Open Android applications Navigate to websites in your web browser all using shell scripts. You can do all that with term mux So check it out term mux. You can get it in the Android that the Google Play Store or as we talked in the last video in f droid Either or make sure you remember which way install it because it does make a difference Once we get a little more into what we're going to be doing in the next video So be sure to come back check that out as always visit films by Chris comm that's Chris the K There's a link in the description, and I hope that you have a great day


There's nothing better than putting in an old VHS tape, you see those old trailers start to play and it just takes you back, it makes you warm and fuzzy inside. It's watching it the way you remembered it. It got the DVD, put it in and it was like, it's not the same because the trailers before the movie is not the same. It wasn't the same viewing experience because those things were part of the viewing experience.


This is a good point to take a break and take some questions. I will go with live questions now and then I will look at chat. L R Tiwari, Meera Road, please go ahead. Sir, you spoke about the research methodology. Why do we need to have a search? This is the basic question I have. Well, research and search are two different things. The goal is to find something new and we saw the Oxford definition of research. There must be something novel here. Search is something different. If you mean web search, that is a different thing. Now, whenever you do research, you have to see what other people have done first because you do not want to reinvent the wheel. If you come up with something which somebody has already done, that is not novel. So, the first part is understanding what other people have done, how far they have reached and what are the gaps. Then you go around finding gaps and filling them. That is a major part of research. Sometimes research can be totally different in the sense when the web came up, the web was not exactly a research project. It was a development project which was done in CERN and it was a tool that was built to help physicists working on shared projects. But then it exploded. Its possibilities were amazing. What was initially just the tool exploded into something much bigger than anyone had thought about. Then there were so many research issues which came up. How to do web search? How do you type a few keywords and find information that you are looking for? Information retrieval is an old area, but it exploded when the web exploded. So, you can have research where there is a real life problem. You do not know how to do it and you figure out how to do it. That is certainly part of research. So, that is one of the two modes I have talked about. That is one mode. The second mode is when you look at what others have done and try to improve on what they have done. I hope that answered your question. Let us move on to at this point to questions related to storage. We have one more session on research. So, I will answer more questions on research tomorrow evening. We have Xavier's Catholic College, Tamil Nadu. Sir, actually you explained about the rate system. Yes. Yes, and you said multiple disks are used in parallel. Yeah. So, what should be the capacity of this individual disk that we should use? Should it all be of same size or different they can be? What should the capacity of the individual disk be? Is that the question? Yes. Yes, sir. For rate system. Yeah. So, the capacity of individual disk depends on the cost of the disk, the reliability of disk and so on. So, what happens is typically the newest disk of highest capacity tend to be a little more expensive. So, if you look at the price per gigabyte of a 3 terabyte disk today, it is higher than that of a 1 terabyte disk. So, depending on how much storage you need, your minimum rate system might support maybe 6 to 8 disks. So, if you need 3 terabytes of usable capacity, you might put in 6 1 terabyte disks and put in in raid 1 or if your data is cold, you might put in maybe 4 1 terabyte disks with one of them acting as parity disks, then your cost comes down. Your write performance may come down, but if your data is mostly videos which somebody is downloading, you are reading, but not writing that often, this is perfectly good. So, that depends on what your application is. So, this capacity which you choose again depends on that. It is more an economic choice than a choice which is based on technology. So, today if I want more capacity from the same box, I do not want to buy a new box, I might buy a 3 terabyte disk, pay a little bit more, but avoid the cost of one more box. Do you have any follow? And on the same topic, so what should be the physical arrangement that we should make if you want to have multiple disks in the raid schemes there? Actually, should it all be of hard disk, what is the real physical arrangement on this? So, typically how you build a raid system, if you buy a server box, that server box has space for a number of disks. Typically, you would put disks of exactly the same type and size so that the performance is uniform. You do not want to mix some slow disk with some hard disk some disk of higher capacity with some disk of lower capacity, you do not want to do that. You would pick identical disk and put them in an into the system. Now, the system will the raid software or the raid hardware, you can buy a hardware card which supports raid or you could do it in software. Software raid is acceptable for many applications, but not for critical databases. So, there is a small chance of data, some updates being lost. So, if you are a bank database, you would definitely not trust it to software raid, but if you have some student data which once in a way if you lose, it is not the end of the world, you might be happy with software raid. And whichever one you use, those 6 or 8 disks which you put in are organized in whatever form, raid 1, raid 5 as appropriate according to your choice. So, the raid systems will allow you to configure it.  Any further questions? Thank you sir. Good morning, we have Bannari Aman, Satyamangalam, please go ahead. Good morning sir. So, what are the difficulties we could face while sustaining relationship among relations in a complex database sir? Relationships amongst relationships in a complex way, I am not sure what you mean by that. Database sir, while creating relationship relations in a complex database. What is the question? What is the issue? What are the difficulties we will be facing? Sir, a question like this is very loosely phrased, like what are the difficulties we will be facing. This is rather loose question in the sense that you know I can tell you that if you are a programmer, you will have difficulty doing joints and things like that. That is not the point. Why did you come up with that particular schema? It was driven by a design process which helped you choose that schema and if that schema was complex, well it is complex and you know that is what you needed, that is the kind of data you wanted to store. Which complex is complex? That is life and then if you have to do joints, that is life. Now, if you find performance problems because of that and you want to deal with that, there are ways around it. There are ways to create materialized views and so forth which can speed up performance in some cases and there are indices you can create which can speed up performance. But it is not driven by you know what are the difficulties? The difficulty is how to quantify? What are the performance issues? What are the overheads on programmers and stuff like that? You have to break it up into pieces and address these individually. Any follow up questions? Thank you sir. Jawaharlal, Institute of Technology, Madhya Pradesh. Sir, there are some other parameters for measuring the performance of a disk. It is exploding, seek time, average time. Can we measure the performance? Sir, the ones which I have given you are fairly comprehensive. There is seek time, access time, this rotational latency and together access time. Then there is the transfer rate for reads and for writes and then there is mean time to failure. Those are the primary metrics for measuring the performance of a disk. I am not aware of any other major ones. There may be some other less important metric, but these are the major ones. Information storage management is a part of database? What do you mean by information storage management? Database is storing data. How are you differentiating data from information? You know, that is something which is up to a higher level, but at the physical level, data is data. Whether data is a record or it is a document or it is an image, that makes a difference on whether you store it in a database or in a file system. So, that is a primary distinction. Good morning sir. Sir, what is the basic difference between land flash and north flash? So, there is a technological difference between it. I mean any of us who is familiar with hardware knows about NAND and NOR gates, but that is not the key thing here. It is not the NAND gates are very different from NOR gate. It is just a terminology and the primary difference between these two is that NOR flash is used to store data in a way which is byte address. So, it looks more or less like regular memory. You can give an address and read it very fast and this is used to store like ROM. Read only memory is often stored in NOR flash. So, you can actually execute a program by reading directly of NOR flash. It is possible. So, some boot loaders and so on may be stored in NOR flash. On the other hand, the byte addressability means that the per byte cost goes up. So, if you want to reduce the per byte cost of flash storage, you use this alternative which is called NAND flash. Again, do not worry about the issue of NAND gate versus NOR gate. Just think of it as terminology. Maybe NAND gates are used, but the key thing here is that it is not byte addressable. So, you can pack the thing very densely in a chip. You can store a lot more data in a particular number of gates with the NAND flash technology than with NOR flash. So, that is what is used for pen drive solid state devices. We have Ohm Institute, please go ahead. Here is Surinder Singh from Ohm OITM, Heshaar Haryana. My question is that what is the difference between server-based RAID and controller-based RAID? Server-based versus controller. So, I think what you are referring to is what is also known as software versus hardware read. So, controller-based RAID means there is a specific controller which is the RAID controller, which implements the RAID subsystem and server-based which I think is the same as software RAID. I am not 100 percent sure about whether this is the same thing, but I think it probably means the same thing. So, in software RAID, you have programs which run in your computer which manage the RAID system. So, the computer knows there are two disks and when you want to write to one disk, it will also write to the other disk. So, you can set up your OS to recognize that these two disks should be treated as one unit for read. So, you might think that both of these would do the same thing, but the key difference is that any good hardware RAID system would have a bit of non-volatile RAM to record in progress writes. Why is this important? It is important because if there is a failure in the middle of the RAID, the RAID system may be left in an inconsistent state. So, if there is a power failure in the middle of a RAID, if the system crashes in the middle of a RAID, you could land up in trouble. So, the good hardware RAIDs, again people say hardware RAID and when you look closer, it is a card, but it does not have non-volatile RAM. So, I would not really count them as proper hardware RAIDs. So, a proper hardware RAID would have this non-volatile RAM. So, that if there is a failure in the middle, you can recover from that failure. So, if you have important data, you should go with hardware RAID. On the other hand, hardware RAID systems also cost money. So, most of our computer systems which do not have such critical data, the last few updates, if you lose it, fine. You are not going to lose sleep over it. So, for all such computer systems, we tend to have software RAID. So, most of our computers in the CS department here run hardware RAID because that is sorry, run software RAID because it is cheaper and good enough for us. Now, if you buy Intel Biosys, many of them support RAID as part of the bios itself. Now, you might think these are hardware RAID, but at least the cheap boards do not really have non-volatile RAM and what they are doing is what the OS would have done. Just write to both copies, if there is a failure, well tough luck. So, you do not get the benefits of non-volatile RAM with the cheap cards. Let us get back to the slides now. Where we left off before taking questions, we saw this slotted page structure which lets us store variable length records in a page. Now, how do you decide which record goes where in a file? So, there are various organizations. In a heap organization, a record can be placed anywhere in the file where there is free space. So, when a record comes in, it stored at any location in the file where there is free space. A common thing is to just keep sequentially adding at the end of the file and once the record goes there, it stays there forever. That is a heap organization. Well, forever meaning until there is a physical reorganization done. Sequential on the other hand stores records in sequential order sorted based on some particular key. So, you choose a key and store it sorted on that thing.  Whatever records are there are sorted, but if you start inserting, updating, deleting records over a period of time, the sorting will tend to get spoiled and then you have to reorganize the file once in a while to bring it back to real sorted order. The last option is hashing where you compute some hash function on one or more attributes of the record and that hash function tells you where the record should go. These were supported in fact oracle I think still supports hashing, but it is no longer encouraged as much for reasons we will see later. Finally, there is a data dictionary storage which is the also called the system catalog which stores all the metadata. So, this is very important because you know we have stored data on disk. If I want to read data from a relation, how do you know where in disk this data is and that information is part of the data dictionaries and the data dictionary has several pieces of information. The first is the names of relations including the names, types and lengths of attributes of each relation. Then you have names and definitions of views, you have integrity constraints. So, these are all logical information about relations. Other logical information includes who are the users, what are their passwords and then the statistical data which is used for query optimization such as how many tuples are there in each relation, what is the distribution of values, how many distinct values are there and so forth. And the next part is the physical file organization information which is very important. How is each relation? So, sequential hash, heap whatever, where is this relation physically? Now, what do I mean by this? If the data is stored as operating system files, this is simply the names of the files containing the data about that relation. If it is stored directly on disk, then this would have to include disk blocks which store data for that particular relation. Then there is information about indices which is the next topic and so forth. Now, all of this information can be stored as relations themselves. So, this is a schema diagram showing the metadata which we saw in the last slide organized as a schema itself. So, you have relation metadata with primary key being relation name. It has number of attributes storage organization location. Then you have attribute metadata whose primary key is relation name and attribute name. And for each attribute type, the position within the record, the length if it is fixed length or maximum length if it is variable length. Then you have index metadata, view metadata, user metadata and so forth. Now, note here that view metadata, I do not have a foreign key to relation meaning I am not tracking which relations are used in the view. If I did the schema diagram would be a little different, but then people are asking me what happens to view an underlying relation is deleted. It would be detected if you had a appropriate schema key. And the last topic for this chapter is storage access. So far we have said how to store data, but how do you access that data? And the way most database systems do it is you do not go and read the data from this every single time you need it. Instead, a data which has been brought from disk is stored in a part of memory called the database buffer. So, when you want to read data, you first check if that particular piece of data is already in the buffer. Maybe somebody else read it and it is there in the buffer. If so, you read it from the buffer. If it is not currently in the buffer, then you read it from disk into the buffer, which of course means if somebody else is already filled the buffer, some other data is filled the buffer, you have to evict some data from the buffer. Operating systems do this too as part of the file system buffer. It is hidden from you and database systems do it for the database buffer. Now, how do you manage space in the buffer? Whenever space is needed for a block which needs to be read in, you have to evict something. And there are several different buffer replacement policies. Now, operating systems typically use least recently used or variants of LRU, approximations of LRU. In operating systems, the idea is that a block which is recently accessed is likely to be accessed again in the near future. Operating systems usually cannot do much better. Actually, they can these days. There is some hacks on top of that. But, by and large, they do not know what the application program is doing. So, they cannot really do more. But, a database system knows exactly what is going on. If you are running a query, the database system knows what the query is. They know what data that query is going to access. They know this query is going to read every single block of this 10 gigabyte relation. If you use LRU, you read the first block, you are reading the relation sequentially. You are not going to read that first block ever again till you finish reading the whole relation. So, LRU turns out to be a very, very bad idea for a relation scan. In fact, what it does is, when you have large relation scans, it evicts all the useful data and keeps a whole lot of useless data in the buffer. So, database systems tend not to use LRU naively, but to use alternative. So, what they do is, first while a block is being used, it is pinned or fixed in memory. So, we have been hearing a lot about spot fixing. So, I could not wait till we got to this slide on pinning or fixing data in the buffer, which has a completely different meaning. It is fixed in buffer. It cannot move out.  In this period, it cannot be removed from the buffer. Now, among those things which are not pinned, you have multiple replacement policies. If you are doing a relation scan, one block after another, as soon as you are done with the block, you might as well throw away that block, because you are not going to look at it again. So, for whatever block was fetched for this scan, can be tossed immediately. Of course, if that block was already there, because it was being used for something else, maybe you do not want to apply toss immediate as this. Toss immediate is closely linked to most recently used, which says that the system must pin the current block and as soon as you are done with it, you throw it out. It is basically the same thing. It is another name. There are some minor differences. And lastly, some pieces of the database are very highly frequently accessed. These include the data dictionary itself. So, what most systems will do is keep the data dictionary blocks in a main memory buffer or they may even read the data from those blocks and create in memory data structures, which are more efficient and then these blocks can be thrown out. And finally, buffer manager also supports forced output of blocks, meaning you can tell the buffer manager, I have updated this block. Now, please write it out to this. I need it, so that if there is a failure after this, the data is safe on this. I will take a few questions related to storage. D. Y. Patil Kolhapur. My question is, we have been talking about data storages and the question is, the recently the new field in data storage or data retrieval is coming on that is digital forensic investigation. So, sir, please would you throw some light on digital forensic investigation. So, digital forensics at the level of data storage, there is many aspects to digital forensics. But the idea is that people may have stored files on their hard disk and maybe they deleted them subsequently, but you still want to find out what they had stored because it is very easy to delete data from a hard disk apparently.  The actual blocks are not overwritten at that point. So, the original data which you had there are there on the underlying blocks. The only catch is that you do not know which blocks are relevant, which blocks were in your file. So, there are, you know, some hacks which can help you partially recover files, even though you have deleted them. And that is important if the, you know, you are looking at a particular hard disk for evidence of some criminal activity, which the person has deleted maybe by, you know, applying these techniques. You can find out that, you know, this file was there, it was deleted, it was unlinked. But by scanning the hard disk, I, you know, find that what looks like part of the free space was actually the header of a file. From that, I can find the other blocks of the file. Some of them may have been overwritten, but at least I can find parts of the file and determine what had been stored there. So, this is part of digital forensics for storage. That is not a topic we are covering here. It is a very specialized topic. Most people will never get to it. However, the relevant part is if you are, if you really want to cover your trail, it is not enough to just remove the file and you are not done. The other part of it is, if you have stored passwords on your machine and your hard disk apparently fails as some problem, you give the hard disk away to a vendor. Well, if you are a high value target, they might, somebody might be able to put some effort and recover stuff which you had on your hard disk and maybe access your bank account. So, those are some risks which people should be aware of when disposing of hard disk. In particular, if you are disposing of hard disk from your college or home with some important information, you should be careful. Any other questions? So, I have one more follow up question. I would also like to know some research avenues if there are any in this field, that is digital forensic investigation. Research avenues in digital forensics. Now, I am not aware of work in this field. This is not an area I have looked at. So, I am not able to guide you on it. So, I am afraid I have to leave it at that. But I will tell you some work in the database area which is there. You can go read it up. There has been some work on how to clean up data thoroughly in such a way that there is no trail left behind. So, which is the opposite problem. It is to help you clean all traces of what you have done. The converse problem is given that somebody has not done such cleaning, can you recover data which was deleted. So, I am not aware of work on the recovery of data which is probably a very important problem even more than cleaning up. The only thing is that the recovery tends to be specific to specific databases, specific data structures and so forth. So, you have to understand those details in order to do any of it. So, when it goes down to very specifics, it is a little harder to do this without some intricate knowledge of the storage structure. So, you have to be prepared to get your hands dirty and understand stuff at a very low level. But yes, I think there are some avenues for doing it both at the level of files in the file system and also storage in a database because databases have tuples which have slotted page structure. So, on the things which we studied, you should be aware of it. So, if you deleted a record in a slotted page structure, if the other records in that page got moved, then there is no hope of to override the gap that it created, there is no hope of recovering it. But if something else happened, then maybe you can still recover it. So, many databases are multi version data, meaning they keep old versions of data around for some time. So, even after you have deleted it, you can recover it from the old version. So, there are some issues at the database level and how to recover data that has been deleted. So, my question is why RAID is so important for database and how to decide which RAID is suitable for which database? Yeah, you do not pronounce it as RAID, RAID. So, why is RAID important? RAID is very important because disks do fail. We have a cluster of 40 machines in our basement which we use for my colleague who has set it up. So, those 40 machines have I think about 120 plus disks and pretty much every month, one or more disks failed out of that 120. Now, if we did not have RAID, we would lose data every month and if you lose data recovering it, setting up the OS again, it is a big headache. It is a lot of manual work. You really cannot afford this kind of data loss in pretty much any setting today. So, RAID is the most widely used thing to prevent data loss when a disk fail. It is a given that disk will fail. So, you have to have RAID. Now, the choice is between different RAID types of performance. There is another kind of choice which is actually relevant in the context of file system that spans many computers. We will talk a little bit about it in the context of big data, but even before that it is worth mentioning that there are distributed file systems that offer distributed RAID. What that means is it is not that copy of the disk is made, but any file block which you keep, they will keep it in more than one location. So, if a disk fails in the overall distributed file system, they can still recover the data without having a one to one mapping. It is not like hardware or the RAID at the level at which we saw it, but similar concepts applied at a different level. So, does that answer your question? So, that is an active area. Sir, one more question related to attributes. How to implement the simple attribute, composite attribute, derived attribute in SQL? So, we saw how to take an ER diagram with these types of attributes and convert it to the normal, first normal form, flatten it out. So, that is pretty much what you would have to do. There are some rare cases where you could use the object relational features of database like PostgreSQL or Oracle, which let you store fields which are multi-valued, but that would be more the exception. You should not do that as a matter of course. Sir, my question was with respect to discrete performances. In Linux, we can increase our discrete performance with the help of block DEV command, that is blocking of IO controls. So, how this can be done with respect to Windows other than the options for disk fragmentation? I am not familiar with Windows at this level. So, I am unable to answer your question. So, the optimizations in the Linux context. So, by default, the Linux file system do a variety of things. So, when you read a file, they are supposed to keep track of the access time. When was the last time the file was accessed, which actually has a very big overhead in some cases. If you are doing a lot of reads, that turns into a lot of updates of the access times of the files. So, one of the optimizations which is available is to turn it off for a particular file system. So, access times are not tracked. And that is very useful in many cases because we do not care about access times. When was the last time you used the access time for a file. Whereas, the update time is something which is very important. There are a few other parameters like this which you can tune to improve the performance of a file system. The Windows equivalents of it, I am not familiar with, unable to answer that part of the question. Put him a college Rajasthan, please go. Sir, my question is how relational databases are stored on disks. In other words, how multiple relations are mapped into disk files. And is there a separate file for each relation of a particular database or multiple relations are stored in a single disk file? That is a good question. So, I showed an abbreviated version of chapter 10 slides. If you see the full version of the slide or if you go to the book for that matter, there is some discussion of this issue. So, restricting ourselves to systems which store data as OS files. The most common situation is that there is one or more files per relation. But two relations cannot share space in a single file. That is the most common kind of setting. So, if you have one relation, it may have 20 files. Another relation may have one file depending on how big it is. Typically, many of these systems will create a directory and start creating files inside the directory as the relation grows, they will create extra files. Now, the other part of the question is, can you have multiple relations stored in a single file? Logically, yes. And practically, some databases allow it. I think Oracle allows this. It is called multi-table clustering. So, if you have two relations which tend to get access together, it is actually more efficient to store the tuples of those two relations plus third together in the same page. So, supposing I have, let us say, a student and the courses that the student has registered for. And these are accessed very frequently together, may be transcripts. Courses registered for is slightly different. But let us say, a student and their transcripts. So, these are very often accessed together. So, it may make sense to store a student tuple with the transcript tuples in the same page. So, this is supported by some database system. There are trade-offs. It will help certain queries. On the other hand, it hurts certain other queries which just want lists of students without getting their transcripts. So, they pay a higher IO cost. So, there is a trade-off. So, that is the end of this chapter.


Alright, baby. It's time to find ourselves a ship right ladies and gentlemen. Welcome back to channel My name is check the bus for I should know me we got episodes 231 232 of our one-piece watch today And the last one we arrived at water seven a beautiful city made out of a fountain We started to get a sort of a lay of the lands met a lot of the shipwrights for our crew hasn't yet But we got an idea of what they all look like and then a very odd interaction in which Robin actually Disappeared after one of the masked individuals in the sea walked by just said see the night very very eerie very intriguing The chopper has lost her and then the very end some random people just stormed going Mary and Zoro's the only one on board So who knows what's gonna happen? We're gonna hop right into if you knew the channel chopper sub and hit that people bell Let's get started I mean I don't want to overestimate Zoro who you can probably take them on most likely I don't know who you guys are but I think you messed with the wrong person. Yeah, they have like Is this like a pirate crew? They have like uniforms Oh, you've heard of him. Oh, even the fishnets Oh, you're one and the same then the Frankie family What is that guy in the middle bro? Has Zoro heard of them if he's so confident. I mean they know who Zoro is and they're confident Which takes a lot.  Oh, man. He's rolling all of them. No, I maybe I don't overestimate Zoro.  I guess it was just because we're in like a new land a new place So maybe like new dangers offer Zoro Oh We've got make some money. There's money. Oh wait. He's got overalls too. He's got similar looking Do they all have glasses like that? We've got a cash out, baby. Cash in cash out cash in cash out. They have so much gold Whatever they they could get like scammed or anything Right where we belong, baby Oh, they're checking to see how much everything's worth, but he's trying to hold it in I won't give him ideas. Usa What is this some crime against like false appraisals? Ah Let's go Oh my gosh. Oh, they're gonna be targeted by everybody. Dude You can do more than fix Mary. You can freaking do anything man. You can get a statue. You can get whatever you want Wait Are we sure it's not worth more than that? It's probably worth more. He's asking for a signature slash thumbprint very quickly. No, I mean stop them Thank you Are you saying that this is worth more than luffy or that luffy's dangerous. She's a ruthless business woman. Let's go nami Let's go. She knew exactly that She knew it was worth more than that didn't say anything until he was ready to sign Oh my gosh, bro We so loaded they just have three briefcases three luffy freaking bounties Oh Luffy, please stop. Please stop. She knew that he was underselling dude. We're so rich Mary's about to get the biggest like makeover of all time Okay, well, yeah, uh luffy can't get in. Oh, okay.  There's so many of them Yeah, who went to the ship? Yeah, that's going real well. Hey, where are we taking it first? Oh the shipyard first You can do more than repair it now like I don't know dude. You could you could like get married in tip-top shape Water buns who stop actually being the responsible one for once. This is incredible So there the inner cut really isn't going to change. It's going to stay as luffy So, I mean it's it's still kind of cool, but I was setting it up for similar to the old ones How was the different character every time? Oh, it's door number one There's still no like mention of the purpose behind the numbers, right? I'm assuming it just details like what everything is or where everything is His name was uh iceberg. Yeah ice pops was the iceberg named in that group. I'm pretty sure he was He's just crawling over. Oh Dang dude. Usopp. Usopp stopped him fast. It doesn't even look like a nose. Are there nostrils? There are no nostrils Gally this guy seems nice. He's got a friendly face Squarish, I guess usop doesn't have any like nostrils either and they're really noticed Yes, we are he has such a kind voice too. I like this guy 23 He's just mature It's on his waist this hip the mayor. Oh shoot President of galila company. Oh the sea train Okay, so yeah, I'm guessing he wasn't introduced in that group Why would what's her name the grandma tell him to find iceberg first inform I guess because he'd be the like most trustworthy and they could approach anyone at the dock shipyard. Is he going? He's gonna go appraise it. Let's go 10 minutes you can make it there and back. I'm sorry. Can you fly sir? Oh my gosh, like lightning. Dang this guy don't mess around Wait, didn't isn't that like a level fall off? This guy's a maniac You could tell this is definitely not his first time doing that He runs freely The mountain wind look at him go Kaku, okay. Who was introducing him sanji just out exploring I guess This is such a lovely place his realty You're gonna have to find Robin first Are they just both lettuce Water water Napa cabbage will sanji ever get like a serious love interest or is he always gonna be like this man?  I just I don't like the way it sounds hubby Bro those fish is chilling in a grocery bag They said most ways to get around you're gonna have to have oh wait Robin's going with the dude that said cp9 Oh, no. Hey, what's going on dude?  What is going on? The whole uh prophecy type thing from shoot. I already forgot. Is that how you say it? The whole prophecy thing with Robin's getting weirder and weirder with this either. She's being tricked into following him Uh, there's some prior engagement something's going on. Dude. He is just like what he looks like wind dude. Kaku's kind of cracked What if Zoro's gonna tell him about what was it the the Frankie family? He's gonna tell him about He's like, yo, what's up with those guys?  No, I kind of compared him. We'll stop right away anyways Thank you, Zora. I'm sorry Oh, this is the guy. Oh wait, these two are shown right? Yeah, the stripes suit Yeah, you gotta be cracked out the wazoo. Oh, yeah, they introduced the both of these califa. What was his name? Oh recognize niko robin I didn't know everything about him Oh, he's iceberg. No, it did say his name. This is a mouse. I found Oh, so this is guy that's in charge That's so cute. So iceberg is the mayor califa seems like his like assistant of sorts Yeah, and he's he's kind of in charge around here. He's also in charge of the train and something else Oh Poochie once again, that's brought up the name drop that town so many times the gourmet town Says you usab, who are you to tell? They have a reference light a letter Oh, it's because they talked bad about him the money usab Dang with that full work sanji sanji gotta we're gonna run for his money. Oh the secretary. I want to be kicked So self-aware man Oh my I kind of like icebergs attitude though.  I can't tell if it's weird or He kind of reminds me of loopy in a sort of way like I'm really they're gonna match the sort of energy Now let's get a tour No shot man You did not just lose a hunter mill dog How does this happen? They're making a Because slow get away. Oh my gosh this family again, man. What the heck? Cause it's money who's up people are shameless And wait, those are the exact same guys that was in the boat too So you're telling me they went to the boat failed got rolled by zoro came to the city or like, all right Let's just find the first people can mess with that. Oh, I guess they did know they were from mary shameless All right episode 232. Let's run it


Here we have the Tadpole Galaxy. Its distorted shape was caused by a small interloper, a very blue, compact galaxy. You'll see it in the upper left corner of the more massive Tadpole Galaxy. Seen shining through the Tadpole's disk, the tiny intruder is likely a hit-and-run galaxy that is now leaving the scene of the accident. Some gravitational forces from the interaction created the long tail of debris, consisting of stars and gas that stretch out more than 280,000 light-years. The other interesting thing here is that most of the stars in the background are galaxies. There are 6,000 galaxies behind the Tadpole, moving very deep into space.


Dumbest Euro player look instead of just flashing it like off of this wall you bounce it low So that way it pops like just barely in the line of sight of the dish here like very well played Perfect flash Yeah Even if it's a fake clone where else would he be?


Live from Las Vegas, Nevada. It's theCUBE, covering EMC World 2015. Brought to you by EMC, Brocade, and VCE. Hey, welcome back everybody. Jeff Frick here, you're watching theCUBE. We're at EMC World 2015 in Las Vegas, Nevada. It's our sixth year coming to EMC World. It's actually where we started theCUBE many moons ago and we're really excited for this next segment to have our very special guest host, David Floyer, CTO and co-founder of Wikibon. Welcome, David. Hi, Jeff. It's great to be back here again. And we've got a special guest today. His name is Tamir Segal, and he is a senior manager of product marketing manager for Extreme I.O. And we're going to discuss business continuity. Yes. And so, introduce yourself and how long have you been with Extreme I.O.? So, my name is Tamir Segal. I'm senior manager of product marketing in Extreme I.O. And actually I joined Extreme I.O. about two years ago, actually more than two years ago. Initially, I was based in Israel as part, I was involved in the product management of Extreme I.O. responsible for all of the Extreme I.O. data services. And I just recently moved to the Bay Area. Ah, welcome. Excellent, welcome. Sticker shock. Yeah. Well, so this whole area of Flash, it's been an exciting journey, hasn't it? What, from a fundamental point of view, what have you observed about Extreme I.O. going in and the impact it's had on the data center and on all the processes within the data center? So we all know that Flash is disruptive. We know that it impacts the entire ecosystem. So it's not only about spin, it's about the entire ecosystem, whether it is the way that people work with snapshots, the way that they design their workflow, and how actually it impacts the application learn as well as the daily work of the people. So it's really disruptive and people need to adapt and change for that. Right, so the traditional way of doing business continuity has always been pretty well replication, hasn't it? Synchronous or asynchronous replication of one sort or another. So what's different about the Flash? It's obviously the architecture of the Flash is different, everything's different about the Flash. Before we dive into the architecture, the first thing that we need to understand about Flash is that Flash is fast, right? So think about how many I.O.s a Flash array can support, million, million point two with Extreme I.O. 8 bricks. So think about the amount of changes that now need to replicate for one minute in on Flash array versus in one minute in a legacy array. Now think about the one usage that it's now requires in order to replicate those one minute of changes. And other things that you need to take into account is the fact that now you have the ability to consolidate many, many, many different mixed workloads into a single platform, and you have many angry I.O.s applications running concurrently, generating a lot of I.O.s and you need to be able to replicate them all together. Now another aspect of it is that now, if you base your I.O., let's say, based on time, you've probably done that because you calculated, okay, what is the cost to my business if I'm losing one minute of data? But now in one minute, you can get much more transactions than that. So your value per minute just goes through the roof, right? Right, so again, it impacts everything, it impacts the one, it impacts the infrastructure, and also you need to take into consideration that once you turn on replication, and again, we're dealing with flash, you don't want that to impact your predicted consistent performance of the old fresh array. You bought everything fast array in order to get really good SLAs sub millisecond latency. You don't want to see spikes once you turn on replication. And that's obviously one of the issues about traditional replication, even on much lower I.O. rates, traditional I.O. rates. So one of the things that I think will be is completely different in the way that you approach things on extreme I.O. And all flash arrays is the use of the snapshots, the space efficient snapshots, which are both read and write. So can you talk a little bit more about the fundamentals of how you would go about replication or how you would go about business continuity with an old flash array? Sure, so what we've done is, again, the Xtumeo snapshots are very unique. We have in-memory metadata snapshot architecture that enables us to create really fast, really rapid creation of snapshots, and we can delete them. So what do you mean by fast? Again, if I create the snapshots, it is immediately available. There's no metadata block involved. There's no copy of metadata involved in that process. Is it a second or five seconds or a second? In terms of the creation, it's immediate. It's like a fraction of a second or a minute second or even less than that. It's really fast. And again, the Xtumeo in-memory metadata enables a lot of flexibility so I can create very complex topology snaps and snaps without any impacts on performance. Then we will get the exact same performance on snapshots the same as you were getting on production volume. Now, think about how I can leverage the Xtumeo in-memory metadata, the ability that we have a way to rapidly create and delete snapshots without impacting the system. Think about how can I leverage that in order to perform replication? So this is exactly what we've done. Basically what we've done is we're leveraging the Xtumeo in-memory metadata together with our in-memory metadata processing capabilities, an API that we developed, and we're leveraging, basically, we merged it with the RecoverPoint technology. And now what we are doing is we are offloading the other tasks of replication to the RecoverPoint appliances. So actually what we are getting is that once we are adding more and more workloads into the Xtumeo of A, we now can scale adding more X bricks, but we can also scale with the replication, adding more LPAs, again getting the same predicted consistent performance as you would like to get it. Right, so you're able to take all of that. Now what does that mean in terms of RPO and RTO? So it's always been a trade-off between the two, hasn't it? You can take, you can replicate synchronously, but as soon as you replicate asynchronously, you really got a very thin pipe, which you're putting a lot of stuff down. And you've always had to trade off RPO and RTO. So how does this work with an all-flash array? So again, the trade-offs are specifically around the RPO. As fine as you want your RPO to be, more costly it will be for you. In terms of the WAN that you need to allocate, so for example, in synchronous application, you need to design your WAN for the maximum peaks that you will have in the system, because again, you will get delayed because you are waiting for acknowledgement from the other side. Right. If you are willing to live with a longer RPO, then you can drive the cost down. So RPO basically is related more to trade-offs on costs. RTO, I don't think you need to compromise on RTO. There's no trade-off between them. The trade-off is within each one of them. So the RTO that we are able to provide are basically immediate. Any snapshot can be accessed immediately. And again, back to the application that we developed using the Coverpoint technology and the native integration with the XMIO. What we are capable of doing is we are able to provide an RPO of 60 seconds or less at scale. Again, we can support the full potential performance of the XMIO already, and we can replicate it entirely using a single Coverpoint cluster. So you RPO at 60 seconds, and then you do another snap, and then you go through that process again. So the fundamentals of how it works basically, we create a snapshot. And then the first time, for the first time, obviously we need to transfer everything to the remote side. There's no magic here. It's not like this, and you can get the data to appear at the other side. So you really need to sync everything to the other side. And then following that, depending on the RPO settings that you have in the consistency group, we have the flexibility to have different protection policies per consistency group. You can replicate the data. We'll create another snapshots using the XMIO in-memory API. Basically, we will query for differences between the snapshots, and we only sync those changes between the two sides. It's going to be really efficient. Back to the RPO questions. Again, one important aspect of it is the cost of one. Again, by the fact that we're leveraging the heavy tasks of applications to the RPAs, we can actually allocate more resources to reduce the bandwidth that we consume. So that's another important aspect of that. So you can get down to now a true RPO of one minute, and that's amazing, isn't it? I mean, that's completely changes the whole landscape for RPO and RTO. And again, you should not think about the legacy array approach. You should think about the whole flesh. Again, they are disruptive. They generate a lot of aisles. You want a sub millisecond. You don't want it to be interrupted. And again, getting a 60 seconds or even less, actually, we are able to support in some cases, actually less than 30 seconds, RPO. It is really important for your business. Again, it minimizes your business risks in case of disaster. So how's that been for your customers? Tell me some examples of whether you're using this, any specific areas where they are specifically using Extreme IO rather than any other approach. So actually, I'll tell you a very interesting story. So part of the unique capability of the extreme array is again, it's the in-memory method at that time, the snapshot creation, the special efficient snapshots that we have in Extreme IO. So one of the more interesting use cases is basically leveraging the DR capabilities, or the DR site, the copy of the DR, in order to create multiple copies for test and depth. So combining DR with test and depth provides you with a lot of cost savings, provide you with the confidence that you have your production pod in tax and you have your DR and test and depth consolidated. And it provides a lot of efficiencies because now we have the specific efficient snapshots, you can create them whenever you want, you can create as many as you want, and they provide you the same performance as production volume. So that's a pretty impressive story. So the speed just opens up all types of new opportunities of the way that you approach the problems? Right, but again, it's not only speed, it's also about the data services, the efficiencies that you get, the inline duplication, the compression, the specific and snapshots, and now the really powerful application capabilities. If you combine them all, I think it's very attractive and unique value proposition for our customers. Right, and like you said, and just because of the density of the application throughput and the capacity, now your value of time goes up significantly. So this announcement of the recover point, that's part of 4.0, is it? It's part of the 4.0 release. It will be available at the end of the quarter. Available at this quarter, wow. At the end of this quarter. At this quarter, and so talk a little bit more about where you put these, with a recover point, my understanding is you can actually, you don't have to put it on extreme IO, you can put it actually any way you want it to, is that right? Yeah, so actually we allow our customers to leverage existing assets, so it is not mandatory to use extreme IO at the DR side. So basically what you could do is you can replicate from extreme IO at the production side, to let's say a VMAX, VNX, or actually third party arrays using Deeplex Vita. So it really allows you a lot of flexibility in terms of using your existing assets. It's mirror, this is the flash story just continues to get better and better. We're getting the hook here, so I want to give you the last word, don't give away any trade secrets, it's going to get you in trouble, but what are some of the next kind of hills you guys are looking to climb? What are some of the challenges that you're excited about over the course of the next six months before we see you again in 2016? So I don't want to get into too much details, but think about how powerful the extreme IO in memory metadata architecture is, what it is enabling, what an API for that can enable us in the future. I think this is where we'll head, we'll continue in investing in more and more data services for the old flash array in order to improve it and provide new services for our customers. Exciting, exciting times, it's already one of the fastest growing, I think they were saying sales in history of EMC, so that's greatness. Thanks for stopping by, appreciate a lot, hopefully you had a good time on theCUBE. David, as always, love to get you out of the analyst meetings, get you on theCUBE. I'm Jeff Frick, you're watching theCUBE, we're at EMC World 2015, we'll be right back with our next guest after this short break, thanks for watching.