Re: AIX/ORACLE - Raid devices + async I/O

In article <CxzsHK.ItE_at_world.std.com>, lparsons_at_world.std.com (Lee E Parsons) wrote:

Hi Lee,

Making one filesysytem is no bad idea but you have to keep in mind these facts:

In 3.2.5 max filesystem size is 2 GByte.
In 3.2.5 max filesize is 2 GByte.
In 4.1.1 max filesystem size is up to 64 GByte (using NBPI ratio 4096)
In 4.1.1 max filesize is 2 GBytes !

So maybe you will not gain anything.

Good luck, please post if you have interesting results.

Toni  

> We are using AIX 3.2.5 and Oracle 7.0.16 and are currently looking at the
> I/O configuration. Couple of quick questions.
>
> 1) The Unix Gang wants to take our raid subsystem and create one filesystem
> across all five drives in the array replacing the 5 filesystems we have
> now. The only thing on this array is oracle datafiles so it sounds like
> a reasonable plan. Instead of having 5 FS's that are striped across
> 5 disks we'll have 1 FS across the same disks.
>
> All things being equal, can anybody think of a good reason not to do
> this?
>
> 2) The Oracle instalation manual make a big todo about the async_io kernel
> extentions. And setting the Oracle initializaion parameter to make use
> of async_io does seem to produce a real performance benefit. This was
> suprising to me since we are not using raw devices and I would have
> expected the FS code to already be asynchronous.
>
> Are not writes to the JFS already async and if so how does the async_io
> option increase performance of I/O?
>
> --
> Regards,
>
> Lee E. Parsons
> Systems Oracle DBA lparsons_at_world.std.com

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