ZFS performance gains real or imaginary?
matt at corp.spry.com
Thu Dec 18 21:37:42 PST 2008
On Dec 18, 2008, at 4:48 PM, Wes Morgan wrote:
>> On the two systems above (amd64 with 16GB of RAM and 24 1TB disks)
>> I get about 30 days of uptime before the system hangs with a ZFS
>> error. They write backups to disk 24x7 and never stop. I could not
>> anything near that level of stability with back03 (below) which was
>> much older hardware maxed out at 4GB of RAM. I finally resolved
>> the stability issues on back03 by ditching ZFS and using
>> geom_stripe across the two hardware RAID arrays.
> Were you doing a zfs mirror across two hardware raid arrays? The
> performance of that type of setup would probably be sub-optimal
> versus a zpool with two raidz volumes.
I haven't benchmarked it with -HEAD but with FreeBSD 7, using a ZFS
mirror across two 12-disk hardware RAID arrays (Areca 1231ML) was
significantly (not quite double) faster than using JBOD and raidz. I
tested a few variations (four disk pools, six disk zpools, 8 disk
I'll be getting another 24 disk system to add to my backup pool in a
month or two. When it arrives, I'll run some additional benchmarks
with -HEAD and see where the numbers fall. I'll be quite surprised if
raidz can outrun a hardware RAID controller with 512MB of BBWC.
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