Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id B9C6C64FC2F for ; Thu, 6 Nov 2008 06:21:49 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 95067-05 for ; Thu, 6 Nov 2008 06:21:49 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from hyperion.scode.org (hyperion.scode.org [85.17.42.115]) by mail.postgresql.org (Postfix) with ESMTP id F313664FC2D for ; Thu, 6 Nov 2008 06:21:48 -0400 (AST) Received: by hyperion.scode.org (Postfix, from userid 1001) id B9D4323C482; Thu, 6 Nov 2008 11:21:47 +0100 (CET) Date: Thu, 6 Nov 2008 11:21:47 +0100 From: Peter Schuller To: David Rees Cc: pgsql-performance@postgresql.org Subject: Re: Occasional Slow Commit Message-ID: <20081106102147.GB70379@hyperion.scode.org> References: <72dbd3150810271723w57859013v9c4e3718ae86fba@mail.gmail.com> <72dbd3150810291530q7a95da64j2c39354de9ad91d1@mail.gmail.com> <72dbd3150810311714s51639bc3kfdbe03a7b51bc55c@mail.gmail.com> <72dbd3150811051925n50ead40cn30354990ebb8bfb6@mail.gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="i0/AhcQY5QxfSsSZ" Content-Disposition: inline In-Reply-To: <72dbd3150811051925n50ead40cn30354990ebb8bfb6@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-Archive-Number: 200811/21 X-Sequence-Number: 31752 --i0/AhcQY5QxfSsSZ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > I also found that my write cache was set to WriteThrough instead of > WriteBack, defeating the purpose of having a BBU and that my secondary > server apparently doesn't have a BBU on it. :-( Note also that several RAID controllers will periodically drop the write-back mode during battery capacity tests. If you care about consistently/deterministically having full performance (with white-backed battery protected caching), you probably want to confirm your controller behavior here. (I've seen this on at least LSI based controllers in Dell 2950:s, and also on some 3wares.) --=20 / Peter Schuller PGP userID: 0xE9758B7D or 'Peter Schuller ' Key retrieval: Send an E-Mail to getpgpkey@scode.org E-Mail: peter.schuller@infidyne.com Web: http://www.scode.org --i0/AhcQY5QxfSsSZ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (FreeBSD) iEYEARECAAYFAkkSxToACgkQDNor2+l1i30TYQCeIau454jkxbpqvkMgX4NXxqwR ymkAnjTUqpLpOViglbcyTuMyg0cgJJZK =FG34 -----END PGP SIGNATURE----- --i0/AhcQY5QxfSsSZ--