Date: Wed, 16 Dec 2009 00:52:53 +0100 From: Solon Lutz <solon@pyro.de> To: Matt Simerson <matt@corp.spry.com> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS RaidZ2 with 24 drives? Message-ID: <957649379.20091216005253@pyro.de> In-Reply-To: <42952D86-6B4D-49A3-8E4F-7A1A53A954C2@spry.com> References: <568624531.20091215163420@pyro.de> <42952D86-6B4D-49A3-8E4F-7A1A53A954C2@spry.com>
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> I deployed using the two configurations you see above. Both machines
> have a pair of Areca 1231ML RAID controllers with super-sized BBWC
> (battery backed write cache). On back01, each controller presents a 12-
> disk RAID-5 array and ZFS concatenates them into the zpool you see
> above. On back02, the RAID controller is configured in JBOD mode and
> disks are pooled as shown.
Why concatenate them into one pool and give up the redundancy?
I have the same setup: Areca 24-port RAID6 (24x 500gb)
NAME STATE READ WRITE CKSUM
temp ONLINE 0 0 24
da0 ONLINE 0 0 48
And it very nearly killed itself after 28 months of flawless duty...
All went fine until 4 drives disconnected themselves from the Areca due
to faulty SATA-cables. This crashed the Areca in such a way, that I had
to disconnect the battery module from the controller in order to get it
initialized during boot-up.
Cache gone - ZFS unable to mount 10TB pool - scrub failed - I/O errors
This was three months ago and if I hadn't found an extremly skilled person
who was able to manually find and distinguish between good and corrupted
meta-data sets, replicate them in their proper spots and zero out corrupt
transaction ids - I would have lost 10TB of data. (No backups - to expensive)
Why do you use JBOD? You can configure a passthrough for all drives,
explicitly degrading the Areca to a dumb sata controller...
Best regards,
Solon Lutz
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