| From: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
|---|---|
| To: | Mark Kirkwood <markir(at)paradise(dot)net(dot)nz> |
| Cc: | Charles Sprickman <spork(at)bway(dot)net>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: SAN/NAS options |
| Date: | 2005-12-16 22:18:01 |
| Message-ID: | 20051216221801.GT53809@pervasive.com |
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| Lists: | pgsql-performance |
On Wed, Dec 14, 2005 at 08:28:56PM +1300, Mark Kirkwood wrote:
> Another interesting thing to try is rebuilding the database ufs
> filesystem(s) with 32K blocks and 4K frags (as opposed to 8K/1K or
> 16K/2K - can't recall the default on 4.x). I found this to give a factor
> of 2 speedup on random disk access (specifically queries doing indexed
> joins).
Even if you're doing a lot of random IO? I would think that random IO
would perform better if you use smaller (8K) blocks, since there's less
data being read in and then just thrown away that way.
> Is it mainly your 2 disk machines that are IOPS bound? if so, a cheap
> option may be to buy 2 more cheetahs for them! If it's the 4's, well how
> about a 2U U320 diskpack from whomever supplies you the Supermicro boxes?
Also, on the 4 drive machines if you can spare the room you might see a
big gain by putting the tables on one mirror and the OS and transaction
logs on the other.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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