On 08/14/11 12:51 AM, Edward Ned Harvey wrote:
From: Ian Collins [mailto:i...@ianshome.com]
Have you already tested it?  Anybody?  Or is it still just theoretical
performance enhancement, compared to using a "normal" sized drive in a
normal mode?
How would you test it?  I guess you would need two pools, 2 SSDs (to
compare) and a lot of small, sync writes.
I would say, one pool, one SSD.  Run iozone.
Then swap the SSD, repeat iozone.

Some people will say bonnie instead of iozone.  In this case, I think either
one is fine.

But would that be an effective test? Unless your data volumes and rates are huge, only a few GB of the log device will be written, so any benefits from overprovisioning would not be seen. I thought wear and performance issues only show up over time, so a lengthy test would be required.

I have a low cost Corsair SSD in use as a ZIL using an 8GB partition. I'll try bonnie before and after filling the rest as a cache.


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