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

Anton Dischner (dischner_at_med.uni-muenchen.de) wrote:
> 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)

                                                        ^^^^

Whats NBPI ratio?

> 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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|  Hamish Marson                                                     |
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