David Brown wrote:
One thing to watch out for when making high-availability systems and
using RAID1 (or RAID10), is that RAID1 only tolerates a single failure
in the worst case. If you have built your disk image spread across
different machines with two-copy RAID1, and a server goes down, then
the rest then becomes vulnerable to a single disk failure (or a single
unrecoverable read error).
It's a different matter if you are building a 4-way mirror from the
four servers, of course.
Just a nit here: I'm looking at "md RAID10" which behaves quite
differently that conventional RAID10. Rather than striping and raiding
as separate operations, it does both as a unitary operation -
essentially spreading n copies of each block across m disks. Rather
clever that way.
Hence my thought about a 16-disk md RAID10 array - which offers lots of
redundancy.
Miles
--
In theory, there is no difference between theory and practice.
In<fnord> practice, there is. .... Yogi Berra
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