DragonFly kernel List (threaded) for 2007-02 DragonFly BSD
DragonFly kernel List (threaded) for 2007-02  Re: Plans for 1.8+
(2.0?)  From: "Chris Csanady" <csanady@xxxxxxxxx> Date: Tue, 20
Feb 2007 10:15:15 -0600  On 2/14/07, Simon 'corecode' Schubert
<corecode@fs.ei.tum.de> wrote:  Chris Csanady wrote: > For
example, consider a 32kB filesystem block. Divide it into 4kB >
sub-blocks, and compute 3 4kB ECC blocks. Now, distribute those
11 > blocks over 11 separate nodes. Any three nodes can fail,
plus space > overhead is only 38% in this case. To provide the
same guarantee with > mirroring would carry a 300% overhead.
While mirroring may be > acceptable in terms of disk space,
network I/O will likely be a > problem.  How do you save on
network IO there?  In the case I presented, less than one third
of the bytes need to be transferred. For N-way mirroring, the
network cost approaches a factor of N more. Also, the larger the
cluster, the larger N must be.  The number of network I/O's is
less significant, and will