Areca vs. ZFS performance testing.

[Nikolay Denev]

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On 8 Jan, 2009, at 02:33 , Danny Carroll wrote:

> I'd like to post some results of what I have found with my tests.
> I did a few different types of tests.  Basically a set of 5-disk tests
> and a set of 12-disk tests.
>
> I did this because I only had 5 ports available on my onboard  
> controller
> and I wanted to see how the areca compared to that.  I also wanted to
> see comparisons between JBOD, Passthru and hardware raid5.
>
> I have not tested raid6 or raidz2.
>
> You can see the results here:
> http://www.dannysplace.net/quickweb/filesystem%20tests.htm
>
> An explanation of each of the tests:
> ICH9_ZFS			5 disk zfs raidz test with onboard SATA
> 				ports.
> ARECAJBOD_ZFS			5 disk zfs raidz test with Areca SATA
> 				ports configured in JBOD mode.
> ARECAJBOD_ZFS_NoWriteCache	5 disk zfs raidz test with Areca SATA 					
> ports configured in JBOD mode and with
> 				disk caches disabled.
> ARECARAID			5 disk zfs single-disk test with Areca
> 				raid5 array.
> ARECAPASSTHRU			5 disk zfs raidz test with Areca SATA 						ports
> configured in Passthru mode.  This
> 				means that the onboard areca cache is
> 				active.
> ARECARAID-UFS2			5 disk ufs2 single-disk test with Areca
> 				raid5 array.
> ARECARAID-BIG			12 disk zfs single-disk test with Areca
> 				raid5 array.
> ARECAPASSTHRU_12		12 disk zfs raidz test with Areca SATA 						ports
> configured in Passthru mode.  This
> 				means that the onboard areca cache is
> 				active.
>
>
> I'll probably be opting for the ARECAPASSTHRU_12 configuration.    
> Mainly
> because I do not need amazing read speeds (network port would be
> saturated anyway) and I think that the raidz implementation would be
> more fault tolerant.  By that I mean if you have a disk read error
> during a rebuild then as I understand it, raidz will write off that
> block (and hopefully tell me about dead files) but continue with the
> rest of the rebuild.
>
> This is something I'd love to test for real, just to see what happens.
> But I am not sure how I could do that.  Perhaps removing one drive,  
> then
> a few random writes to a remaining disk (or two) and seeing how it  
> goes
> with a rebuild.
>
> Something else worth mentioning.   When I converted from JBOD to
> passthrough, I was able to re-import the disks without any problems.
> This must mean that the areca passthrough option does not alter the  
> disk
> much, perhaps not at all.
>
> After a 21 hour rebuild I have to say I am not that keen to do more of
> these tests, but if there is something someone wants to see, then I'll
> definitely consider it.
>
> One thing I am at a loss to understand is why turning off the disk
> caches when testing the JBOD performance produced almost identical  
> (very
> slightly better) results.  Perhaps it was a case of the ZFS internal
> cache making the disks cache redundant?  Comparing to the ARECA
> passthrough (where the areca cache is used) shows again, similar  
> results.
>
> -D
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There is a big difference betweeen hardware and ZFS raidz with 12 disk  
on the get_block test,
maybe it would be interesting to rerun this test with zfs prefetch  
disabled?

- --
Regards,
Nikolay Denev




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