 When compared to main memory, hard disk drive read/writes are slow and random accesses require expensive disk seeks; as a result, larger amounts of main memory bring performance improvements as more data can be cached in memory.Separate disk caching is provided on the hardware side, by dedicated RAM or NVRAM chips located either in the disk controller (in which case the cache is integrated into a hard disk drive and usually called disk buffer), or in a disk array controller.Such memory should not be confused with the page cache.