Chris,
You should be fine.
For each Postgres block you are reading 2 OS blocks.
That's fine. The other way around would be bad.
The optimal RAID block size depends on things like read
ahead algorithms for large sequential reads.
If it ain't broke, don't fix it.
Regards,
Nikolaus Dilger
On Fri, 16 August 2002, Chris Ruprecht wrote:
>
> Thanks Curt - yes, I have the log files on a different
> drive all together.
> I was thinking more along the lines of OS block size
(4
> KB) vs. Postgres block
> size (8 KB by default) vs. RAID block size (32 KB). Is
> there anything I
> should change?
>
> I would like to experiment but a 20 GB DB takes some
> time to backup and
> restore, so I'd like to tap into other's experiences.
>
> Best regards,
> Chris
>
>
>
> On Sun August 11 2002 23:30, you wrote:
> > On Mon, 12 Aug 2002, Chris Ruprecht wrote:
> > > I have set up a RAID-5 (soft RAID) arrray
on my
> Linux machine,
> > > consisting of 5 18 GB UltraSCSI-2 (80
MB/sec)
> drives. Everythinng is
> > > working but I would like to know, where I
can tweak
> this for optimum
> > > performance.
> >
> > If you do a lot of inserts, move the log file
> ($PGDATA/pg_xlog)
> > off the RAID-5 and on to a separate RAID-1
(mirrored)
> pair. This will
> > separate the buffered random writes to the data
files
> and the unbuffered,
> > sequential writes to the log.
> >
> > cjs
>
>
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