Re: OT: high WIO on Linux
- From: "Christo Kutrovsky" <kutrovsky.oracle@xxxxxxxxx>
- To: kevinc@xxxxxxxxxxxxx
- Date: Wed, 15 Mar 2006 15:47:23 -0500
Yes i've noticed that 2.4 is not "optimal" to be polite.
The SAN we have does not have average IO size. I know for sure 2.6 is
way better on large IOs, I just dont know wether I can fully thrust
iostat. What's your observeation with RH4 and the 2.6 kernel ?
On 3/15/06, Kevin Closson <kevinc@xxxxxxxxxxxxx> wrote:
> >>>I've always wondered that. How can you determine that? Is
> >>>the iostat average IO size per device any good for this ?
> >>>
> >>>Sometimes even if it does chew it up in 64k requests, I find
> >>>it's better to have it large, so that you can queue up a
> >>>large number of IOs in a serial read process.
> >>>
>
> iostat -x will help you resolve that. Some of the
> many SANs we have inhouse here also report out what the
> average transfer size is...and if I'm doing, say,
> a CCF or LWS, I should be hitting the array at 1MB, but
> if I'm on something like RH3 (puke all over please so I don't
> have to) it'll be more like 32KB or 64KB "chunklets"...
>
> The 2.6 kernel is not so messed up this way. You are right too,
> that even if it gets chopped down into smaller requests, it is
> still better to have Oracle through out the larger requests.
>
>
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
--
Christo Kutrovsky
Senior Database/System Administrator
The Pythian Group
--
//www.freelists.org/webpage/oracle-l
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