On Tue, Oct 11, 2011 at 6:25 AM, <deg...@free.fr> wrote:
> I'm not familiar with ZFS stuff, so I'll try to give you as much as info I
> can get with our environment
> We are using a ZFS pool as a VLS for a backup server (Sun V445 Solaris 10),
> and we are faced with very low read performance (whilst write performance is
> much better, i.e : up to 40GB/h to migrate data onto LTO-3 tape from disk,
> and up to 100GB/h to unstage data from LTO-3 tape to disk, either with Time
> Navigator 4.2 software or directly using dd commands)
> We have tunned ZFS parameters for ARC and disabled preftech but performance
> is poor. If we dd from disk to RAM or tape, it's very slow, but if we dd from
> tape or RAM to disk, it's faster. I can't figure out why. I've read other
> posts related to this, but I'm not sure what can of tuning can be made.
> For disks concern, I have no idea on how our System team created the ZFS
> volume.
> Can you help ?
If you can, please post the output from `zpool status` so we know
what your configuration is. There are many ways to configure a zpool,
some of which have horrible read performance. We are using zfs as
backend storage for NetBackup and we do not see the disk storage as
the bottleneck except when copying from disk to tape (LTO-3) and that
depends on the backup images. We regularly see 75-100 MB/sec
throughput disk to tape for large backup images. I rarely see LTO-3
drives writing any faster than 100 MB/sec.
100 MB/sec. is about 350 GB/hr.
75 MB/sec. is about 260 GB/hr.
Our disk stage zpool is configured for capacity and reliability and
not performance.
pool: nbu-ds0
state: ONLINE
scrub: scrub completed after 7h9m with 0 errors on Thu Sep 29 16:25:56 2011
config:
NAME STATE READ WRITE CKSUM
nbu-ds0 ONLINE 0 0 0
raidz2-0 ONLINE 0 0 0
c3t5000C5001A67AB63d0 ONLINE 0 0 0
c3t5000C5001A671685d0 ONLINE 0 0 0
c3t5000C5001A670DE6d0 ONLINE 0 0 0
c3t5000C5001A66CDA4d0 ONLINE 0 0 0
c3t5000C5001A66A43Bd0 ONLINE 0 0 0
c3t5000C5001A66994Dd0 ONLINE 0 0 0
c3t5000C5001A663062d0 ONLINE 0 0 0
c3t5000C5001A659F79d0 ONLINE 0 0 0
c3t5000C5001A6591B2d0 ONLINE 0 0 0
c3t5000C5001A658481d0 ONLINE 0 0 0
c3t5000C5001A4C47C8d0 ONLINE 0 0 0
raidz2-1 ONLINE 0 0 0
c3t5000C5001A6548A2d0 ONLINE 0 0 0
c3t5000C5001A6546AAd0 ONLINE 0 0 0
c3t5000C5001A65400Ed0 ONLINE 0 0 0
c3t5000C5001A653B70d0 ONLINE 0 0 0
c3t5000C5001A6531F5d0 ONLINE 0 0 0
c3t5000C5001A64332Ed0 ONLINE 0 0 0
c3t5000C500112A5AF8d0 ONLINE 0 0 0
c3t5000C5001A5D61A8d0 ONLINE 0 0 0
c3t5000C5001A5C5EA9d0 ONLINE 0 0 0
c3t5000C5001A55F7A6d0 ONLINE 0 0 0 114K repaired
c3t5000C5001A5347FEd0 ONLINE 0 0 0
spares
c3t5000C5001A485C88d0 AVAIL
c3t5000C50026A0EC78d0 AVAIL
errors: No known data errors
--
{--------1---------2---------3---------4---------5---------6---------7---------}
Paul Kraus
-> Senior Systems Architect, Garnet River ( http://www.garnetriver.com/ )
-> Sound Coordinator, Schenectady Light Opera Company (
http://www.sloctheater.org/ )
-> Technical Advisor, RPI Players
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