On Fri, 15 Dec 2006, Jesus Cea wrote:
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> I'm interesting in ZFS redundancy when vdev's are "remote". The idea,
> for example, is use vdev remote mirroring as a cluster FS layer. Or
> puntual backup.
>
> Has anybody tried to mount an iscsi target as a ZFS device?. Are machine
> reboots / conectivity problems gracefully managed by ZFS?.
I've been using it with Solaris 10 6/06 on a T1000, with
a pair of Promise VTrak 500i iSCSI boxes as the targets.
I set up the VTraks identically (RAID5E-something, ~4TB each),
filled one with about 3.5TB worth of data, then attached the
other one as a mirror. Shortly after the mirror silvering began,
performance dropped considerably ('zpool iostat 1' wrote a line
of output once every 5 minutes. It took about 3 days to finish
during which the T1000 was basically unusable. (during that time,
sendmail managed to syslog a few messages about how it
was skipping the queue run because the load was at 200 :-)
Once the mirror was synced, I disconnected one of the iSCSI boxes
(pulled the ethernet plug from one of the VTraks), did some I/O
on the volume, and Solaris paniced. After it rebooted, I did a
'zpool scrub' and the T1000 again went into la-la land while the
scrubbing occurred.
I've given up on the mirrored iSCSI idea for now, and am just using
a single VTrak for backups. It's been stable; not the fastest
thing, but I haven't attempted any tuning (no zil tweaking or anything
like that), so I won't complain too much about speed.
I'd really like the 'panic-on-drive-failure/disappearance' behaviour
to change. Now that U3 is out, I'll be giving it another try.
James
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