Received: from makus.postgresql.org (makus.postgresql.org [98.129.198.125]) by mail.postgresql.org (Postfix) with ESMTP id 427101A3D38D for ; Sat, 28 Jul 2012 13:14:13 -0300 (ADT) Received: from sss.pgh.pa.us ([66.207.139.130]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1Sv9ee-0000g2-PJ for pgsql-performance@postgresql.org; Sat, 28 Jul 2012 16:14:13 +0000 Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.5/8.14.5) with ESMTP id q6SGDsYB029997; Sat, 28 Jul 2012 12:13:54 -0400 (EDT) From: Tom Lane To: David Barton cc: pgsql-performance@postgresql.org Subject: Re: Postgres 9.1.4 - high stats collector IO usage In-reply-to: <50136B8D.7070502@oneit.com.au> References: <50136B8D.7070502@oneit.com.au> Comments: In-reply-to David Barton message dated "Sat, 28 Jul 2012 12:33:17 +0800" Date: Sat, 28 Jul 2012 12:13:54 -0400 Message-ID: <29996.1343492034@sss.pgh.pa.us> X-Pg-Spam-Score: -1.9 (-) X-Archive-Number: 201207/349 X-Sequence-Number: 47530 David Barton writes: > I am running postgres 9.1.4 on Ubuntu 12.04 and the stats collector is > generating very high IO usage even when nothing appears to be happening > on the system. > I have roughly 150 different databases, each of which is running in 1 of > roughly 30 tablespaces. The databases are small (the dump of most is > are under 100M, and all but 3 are under 1G, nothing larger than 2G). That's a lot of databases. I think your problem probably stems from autovacuum madly trying to cover all of them. Backing off (increasing) autovacuum_naptime to slow its cycle might help. regards, tom lane