Ahmed Kamal writes:
> Hi,
>
> I have been doing some basic performance tests, and I am getting a big hit
> when I run UFS over a zvol, instead of directly using zfs. Any hints or
> explanations is very welcome. Here's the scenario. The machine has 30G RAM,
> and two IDE disks attached. The disks have 2 fdisk partitons (c4d0p2,
> c3d0p2) that are mirrored and form a zpool. When using filebench with 20G
> files writing directly on the zfs filesystem, I get the following results:
>
> RandomWrite-8k: 0.8M/s
> SingleStreamWriteDirect1m: 50M/s
> MultiStreamWrite1m: 51M/s
> MultiStreamWriteDirect1m: 50M/s
>
> Pretty consistent and lovely. The 50M/s rate sounds pretty reasonable, while
> the random 0.8M/s is a bit too low ? All in all, things look ok to me though
> here
>
> The second step, is to create a 100G zvol, format it with UFS, then bench
> that under same conditions. Note that this zvol lives on the exact same
> zpool used previously. I get the following:
>
> RandomWrite-8k: 0.9M/s
> SingleStreamWriteDirect1m: 5.8M/s (??)
> MultiStreamWrite1m: 33M/s
> MultiStreamWriteDirect1m: 11M/s
>
The straight ZVOL case might have unfairly benefited from
6770534 - zvols do not observe O_SYNC semantic
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6770534
Commited to fix in the next ONNV build (106).
The UFS over ZVOL would not since the strategy entry points
to zvol are not impacted by the bug.
-r
> Obviously, there's a major hit. Can someone please shed some light as to why
> this is happening ? If more info is required, I'd be happy to test some more
> ... This is all running on osol 2008.11 release.
>
> Note: I know ZFS autodisables disk-caches when running on partitions (is
> that slices, or fdisk partitions?!) Could this be causing what I'm seeing ?
>
> Thanks for the help
> Regards
> <div dir="ltr">Hi,<br><br>I have been doing some basic performance tests,
> and I am getting a big hit when I run UFS over a zvol, instead of directly
> using zfs. Any hints or explanations is very welcome. Here's the
> scenario. The machine has 30G RAM, and two IDE disks attached. The disks
> have 2 fdisk partitons (c4d0p2, c3d0p2) that are mirrored and form a zpool.
> When using filebench with 20G files writing directly on the zfs filesystem,
> I get the following results:<br>
> <br>RandomWrite-8k: 0.8M/s<br>SingleStreamWriteDirect1m:
> 50M/s<br>MultiStreamWrite1m:
> 51M/s<br>MultiStreamWriteDirect1m: 50M/s<br><br>Pretty consistent and
> lovely. The 50M/s rate sounds pretty reasonable, while the random 0.8M/s is
> a bit too low ? All in all, things look ok to me though here<br>
> <br>The second step, is to create a 100G zvol, format it with UFS, then
> bench that under same conditions. Note that this zvol lives on the exact
> same zpool used previously. I get the
> following:<br><br>RandomWrite-8k: 0.9M/s<br>
>
> SingleStreamWriteDirect1m: 5.8M/s (??)<br>
> MultiStreamWrite1m: 33M/s<br>
> MultiStreamWriteDirect1m: 11M/s<br><br>Obviously, there's a major hit.
> Can someone please shed some light as to why this is happening ? If more
> info is required, I'd be happy to test some more ... This is all running
> on osol 2008.11 release.<br>
> <br>Note: I know ZFS autodisables disk-caches when running on partitions (is
> that slices, or fdisk partitions?!) Could this be causing what I'm
> seeing ?<br><br>Thanks for the help<br>Regards<br></div>
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss@opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
