ZFS performance on 7.2-release/amd64 low compared to UFS2 + SoftUpdates

[Joe Koberg]

The difference in layout can easily explain a 2x difference in 
sequential transfer performance.

I seriously doubt your disk is really getting 23K seeks/s done in the 
UFS case - 100/s sounds much more reasonable for real hardware. Perhaps 
the results of caching?


Joe Koberg




Dan Naumov wrote:
> I am wondering if the numbers I am seeing is something expected or is
> something broken somewhere. Output of bonnie -s 1024:
>
> on UFS2 + SoftUpdates:
>
>               -------Sequential Output-------- ---Sequential Input-- --Random--
>               -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
>          1024 56431 94.5 88407 38.9 77357 53.3 64042 98.6 644511 98.6 23603.8 243.3
>
> on ZFS:
>
>               -------Sequential Output-------- ---Sequential Input-- --Random--
>               -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
>          1024 22591 53.7 45602 35.1 14770 13.2 45007 83.8 94595 28.0 102.2  1.2
>
>
> atom# cat /boot/loader.conf
> vm.kmem_size="1024M"
> vm.kmem_size_max="1024M"
> vfs.zfs.arc_max="96M"
>
> The test isn't completely fair in that the test on UFS2 is done on a
> partition that resides on the first 16gb of a 2tb disk while the zfs
> test is done on the enormous 1,9tb zfs pool that comes after that
> partition (same disk). Can this difference in layout make up for the
> huge difference in performance or is there something else in play? The
> system is an Intel Atom 330 dualcore, 2gb ram, Western Digital Green
> 2tb disk. Also what would be another good way to get good numbers for
> comparing the performance of UFS2 vs ZFS on the same system.
>
>
> Sincerely,
> - Dan Naumov
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