On Aug 21, 2009, at 6:34 PM, Tim Cook <t...@cook.ms> wrote:
On Fri, Aug 21, 2009 at 5:26 PM, Ross Walker <rswwal...@gmail.com>
wrote:
On Aug 21, 2009, at 5:46 PM, Ron Mexico <no-re...@opensolaris.org>
wrote:
I'm in the process of setting up a NAS for my company. It's going to
be based on Open Solaris and ZFS, running on a Dell R710 with two
SAS 5/E HBAs. Each HBA will be connected to a 24 bay Supermicro JBOD
chassis. Each chassis will have 12 drives to start out with, giving
us room for expansion as needed.
Ideally, I'd like to have a mirror of a raidz2 setup, but from the
documentation I've read, it looks like I can't do that, and that a
stripe of mirrors is the only way to accomplish this.
Why?
Because some people are paranoid.
If that is the case how about a separate zpool of large SATA disks and
either snapshot and send/recv to it, or use AVT to replicate to it.
It uses as many drives as a RAID10, but you loose 1 more drive of
usable space then RAID10 and you get less then half the performance.
And far more protection.
It's not worth the cost, the complexity is so high that it itself will
be a point of failure and performance is too low for it to be any use.
You might be thinking of a RAID50 which would be multiple raidz
vdevs in a zpool, or striped RAID5s.
If not then stick with multiple mirror vdevs in a zpool (RAID10).
-Ross
Raid10 won't provide as much protection. Raidz21, you can lose any
4 drives, and up to 14 if it's the right 14. Raid10, if you lose
the wrong two drives, you're done.
Setup a side raidz2 zpool of SATA disks, snap the RAID10 and zsend it
to the other pool. In the event of catastrophy you can run off the
raidz2 pool temporarily until the mirror pool is fixed (and it would
still perform better then the mirrored raidz2 setup!).
-Ross
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