On Mon, 2010-07-19 at 01:28 -0700, tomwaters wrote:
> Hi guys, I am about to reshape my data spool and am wondering what
> performance diff. I can expect from the new config. Vs. The old.
>
> The old config. Is a pool of a single vdev of 8 disks raidz2.
> The new pool config is 2vdev's of 7 disk raidz2 in a single pool.
>
> I understand it should be better with higher io throughput....and better
> read/write rates...but interested to hear the science behind it.
>
> I have googles and read the ifs best practice guide and evil tuning, but
> neither cover my question.
>
> Appreciate any advice.
>
> FYI, it's just a home server....but I like it.
Very simple. 2vdevs gives 2 active "spindles", so you get about twice
the performance of a single disk.
raidz2 generally gives the performance of a single disk.
For high performance, if you can sacrifice the storage, I recommend a
vdev made up of two-drive mirrors. This gives pretty good resilience,
and good performance. (Its not as "safe" as say raidz2, though, because
with raidz2 you can lose two drives per vdev, where as with mirrors, you
have many more vdevs and can only lose one drive.)
With those same 14 drives, you can get 7x the performance instead of 2x
the performance by using mirrors instead of raidz2.
-- Garrett
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