Areca vs. ZFS performance testing.

[Jan Mikkelsen]

Hi,

Wes Morgan wrote:
> On Sun, 16 Nov 2008, Matt Simerson wrote:
> 
> > The Areca cards do NOT have the cache enabled by default. I 
> ordered the 
> > optional battery and RAM upgrade for my collection of 
> 1231ML cards. Even with 
> > the BBWC, the cache is not enabled by default. I had to go 
> out of my way to 
> > enable it, on every single controller.
> 
> Are you using these areca cards successfully with large 
> arrays? I found a 
> 1680i card for a decent price and installed it this weekend, 
> but since 
> then I'm seeing the raidz2 pool that it's running hang so 
> frequently that 
> I can't even trust using it. The hangs occur in both 7-stable and 
> 8-current with the new ZFS patch. Same exact settings that 
> have been rock 
> solid for me before now don't want to work at all. The drives 
> are just set 
> as JBOD -- the controller actually defaulted to this, so I 
> didn't have to 
> make any real changes in the BIOS.
> 
> Any tips on your setup? Did you have any similar problems?

I am seeing I/O related lockups on 7.1-PRE with an Areca ARC-1220 controller
and eight drives in a RAID-6 array.  The same hardware works fine with 6.3.

When I run gstat while it is happening I see I/O performance drop and the
time to service each write (ms/w) goes up, and then suddenly goes back down
to a sensible value.  I have seen it get to about 22000ms.

The system is essentially unusable for writes, which limits the utility a
bit.  Reads seem fine.

Is this similar to the behaviour you saw?

Thanks,

Jan Mikkelsen