Re: Is this hardware issue?
Date: Mon, 22 Aug 2011 14:46:26 -0500
Message-ID: <CAAKoEZ_nt4oves92kVzBdmgh1MT_Xj9Qk90T-bovUTUNeRxy+A_at_mail.gmail.com>
I understand once the data is cached it can be retrieved quickly from the buffers. I am wondering why it would take 7/8 minutes to get some data from the IO layer. This behavior is NOT the case in the old hardware. It comes back much faster. The plans are same, once again.
On Mon, Aug 22, 2011 at 2:20 PM, Blanchard, William G < William.Blanchard_at_fisglobal.com> wrote:
> This is expected behavior. The first time you run the query, it has to
> read everything into the buffer cache (db file sequential read). Every time
> after that (especially since nobody else is using the database) the
> information for the query is already cached and can be read right from the
> cache.****
>
> ** **
>
> ** **
>
> WGB****
>
> ** **
>
> ** **
>
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Ram K
> *Sent:* Monday, August 22, 2011 2:14 PM
> *To:* oracle-l
> *Subject:* Is this hardware issue?****
>
> ** **
>
> List,
>
> We are moving our stuff from old hardware to a new hardware. I am observing
> these results in our new test hardware env: we run a query in the new test
> env, it runs slow first time it is run. It takes about 6/8 minutes. Once the
> query is run once, if it is ran again, it comes with results in matter of
> seconds. This happens a few times and then I flush the buffer cache or
> bounce the DB and rerun the query, the response time goes back to 7/8
> minutes and the subsequent responses are in matter of seconds. I was able to
> repeat this behavior a few days. I ran the 10046 and checked the plans. The
> plans in both cases are same. The increased wait seemed to come from waiting
> longer for the same "db file sequential read" event. Could this point to
> hardware issues, like I/O or VIO?
>
> No other user is using the database when I do this test, v10.2. OS is AIX,
> disks on Clarion SAN. Although there are couple of other databases running
> in this test server, there is no load from them in terms of CPU or memory. I
> tested in during normal hours, after hours when no one uses any of the DBs
> in the server. The results are consistent.
>
> --
> Thanks,
> Ram.
>
>
> ****
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-- Thanks, Ram. -- http://www.freelists.org/webpage/oracle-lReceived on Mon Aug 22 2011 - 14:46:26 CDT