| From: | Craig James <cjames(at)emolecules(dot)com> |
|---|---|
| To: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
| Cc: | Evgeny Shishkin <itparanoia(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Two identical systems, radically different performance |
| Date: | 2012-10-08 23:03:53 |
| Message-ID: | CAFwQ8reOc-ntKsLRSqVOf81FsGRA_OiVbusDduB2BuH_SzdNGQ@mail.gmail.com |
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| Lists: | pgsql-performance |
On Mon, Oct 8, 2012 at 3:50 PM, Claudio Freire <klaussfreire(at)gmail(dot)com>wrote:
> On Mon, Oct 8, 2012 at 7:48 PM, Craig James <cjames(at)emolecules(dot)com> wrote:
> >> > # blockdev --getra /dev/sdb1
> >> > 256
> >>
> >>
> >> It's probably this. 256 is way too low to saturate your I/O system.
> >> Pump it up. I've found 8192 works nice for a system I have, 32000 I
> >> guess could work too.
> >
> >
> > But again ... the two systems are identical. This can't explain it.
>
> Is the read-ahead the same in both systems?
>
Yes, as I said in the original reply (it got cut off from your reply):
"Same on both servers."
Craig
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