On Sep 11, 2009, at 3:27 PM, Ross Walker wrote:
On Fri, Sep 11, 2009 at 3:01 PM, glidic anthony
<[email protected]> wrote:
Hi all i have make an opensolaris file server and i use comstar.
The first tume i try comstar i have performance nearly 100/110 mb/s
or now i have remake a file server with a different configuration
and the comstar performance is only 10/20 mb/s.
I don't understand why.
Was the first time you built it with OpenSolaris 2008.11 and the
second time with 2009.06?
There was a change in how ZVOL devices behave between 2008.11 and
2009.06 that makes all ZVOL IO synchronous now for data safety.
You can try adding an SSD device as an slog device to the pool.
I've been bitten by the bug fix (6770534) you mention, but while using
the legacy iscsi target server. The exported LUNs comprise a ZFS file
system on the remote client.
Performance is so dismal that I have to stay away from any version of
the ZFS driver that has that bug fix in it. I mean, the enforcement of
synchronous IO, while understandable, just causes IO performance on
the iscsi clients to plummet.
Short of buying SSD for a zil log device, which in all of my servers
there is no physical room for, there is no recourse at all?
Because my clients are using ZFS on those LUNs, I've investigated the
fast write ack option that you can set via iscsitadm, but that appears
to make no difference in IO performance.
This synchronous IO performance, while perhaps a proper thing, just
kills performance.
/dale
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