Received: from magus.postgresql.org (magus.postgresql.org [87.238.57.229]) by mail.postgresql.org (Postfix) with ESMTP id 81F13FA6B99 for ; Thu, 22 Mar 2012 07:33:12 -0300 (ADT) Received: from rs133.luxsci.com ([72.32.115.26]) by magus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1SAfKO-0006Hk-Vb for pgsql-performance@postgresql.org; Thu, 22 Mar 2012 10:33:11 +0000 Received: from GNANAM (NSG-Static-233.156.72.182.airtel.in [182.72.156.233] (may be forged)) (authenticated bits=0) by rs133.luxsci.com (8.13.8/8.13.8) with ESMTP id q2MAWJIG014815; Thu, 22 Mar 2012 05:32:45 -0500 Reply-To: From: "Gnanakumar" To: "'Tomas Vondra'" , "'Vitalii Tymchyshyn'" Cc: References: <006301cd07fd$358ebe40$a0ac3ac0$@com> <4F6AF3FE.30407@gmail.com> In-Reply-To: Subject: Re: Write workload is causing severe slowdown in Production Date: Thu, 22 Mar 2012 16:02:00 +0530 Organization: Zoniac Software Private Limited Message-ID: <008e01cd0817$06418680$12c49380$@com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: Ac0IEzuLj2rmeSYLSQGOWlEGMCjQXgAAo8FA Content-Language: en-us X-Lux-Comment: Message q2MAWJIG014815 sent by user #22393 X-Pg-Spam-Score: -1.9 (-) X-Archive-Number: 201203/142 X-Sequence-Number: 46592 > There's a checkpoint_warning option. Set it to 3600 and you should get > messages in the log. Correlate those to the issues (do they happen at = the > same time?). After setting "checkpoint_warning" to 3600, can you explain on how do I = correlate with the messages? > If you can, install iotop and watch the processes that cause the I/O. I tried installing "iotop", but it failed to run because it requires = Linux >=3D 2.6.20. Our CentOS5.2 is 2.6.18-8. > What we need is more details about your setup, especially > - checkpoint_segments > - checkpoint_timeout > - shared_buffers # - Memory - shared_buffers=3D1536MB # - Planner Cost Constants - effective_cache_size =3D 4GB # - Checkpoints - checkpoint_segments=3D32 checkpoint_timeout=3D5min checkpoint_warning=3D270s # - Background writer - bgwriter_delay =3D 200ms bgwriter_lru_percent =3D 1.0 bgwriter_lru_maxpages =3D 5 bgwriter_all_percent =3D 0.333 bgwriter_all_maxpages =3D 5 > also it'd be nice to have samples from the vmstat/iostat and messages = from > the log. Unfortunately, I don't have "exact" logs when the problem actually = happened