Received: from localhost (maia-2.hub.org [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 51A1F9FB8A5 for ; Tue, 3 Jul 2007 12:07:27 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 38983-01-10 for ; Tue, 3 Jul 2007 12:07:15 -0300 (ADT) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.4 Received: from wx-out-0506.google.com (wx-out-0506.google.com [66.249.82.235]) by postgresql.org (Postfix) with ESMTP id 818359FB88B for ; Tue, 3 Jul 2007 12:07:15 -0300 (ADT) Received: by wx-out-0506.google.com with SMTP id h29so1380191wxd for ; Tue, 03 Jul 2007 08:07:12 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding:sender; b=ofQ+jl8fCrxKYJhfYrXv2d4CrltVsN2Z1UiJkbVKDSqYY3hrMzj8r67IvMUNx+tC3rkX3nE6ltZSL/r1Lnso9RO3r9VV26GrCaEicxMcT93hYbIy91nVTzvU7zDX9gZaSvab5knmNtxg+Y/aZZw+mqKOo23tXYbskjjPy/m2COc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding:sender; b=VrNTcLP2kkexXOcAtGA2j4xTVMrpTTuEf4U0v0/tuveS9d4nP/ldA4W6iOAu+If2byGQFk7C2JRgeOuyegRfxqfHeQxQ3ox0rSGtyDz0mGuLrVMhFIwKP/bXJc2Ix76l50S2yJmgfto8Dl8v1Dqq9CLH0ChXsCNEx7QwIq5ipEk= Received: by 10.90.105.19 with SMTP id d19mr6223005agc.1183475232769; Tue, 03 Jul 2007 08:07:12 -0700 (PDT) Received: from ?192.168.1.36? ( [86.27.186.123]) by mx.google.com with ESMTP id k9sm6426533nfh.2007.07.03.08.07.11 (version=SSLv3 cipher=RC4-MD5); Tue, 03 Jul 2007 08:07:11 -0700 (PDT) Message-ID: <468A65F5.8020800@enterprisedb.com> Date: Tue, 03 Jul 2007 16:06:29 +0100 From: Heikki Linnakangas User-Agent: Icedove 1.5.0.10 (X11/20070329) MIME-Version: 1.0 To: Dimitri CC: PostgreSQL Performance Subject: Re: Filesystem Direct I/O and WAL sync option References: <5482c80a0707030754o740c82b6s4598dc668720d014@mail.gmail.com> In-Reply-To: <5482c80a0707030754o740c82b6s4598dc668720d014@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200707/10 X-Sequence-Number: 25694 Dimitri wrote: > I'm very curious to know if we may expect or guarantee any data > consistency with WAL sync=OFF but using file system mounted in Direct > I/O mode (means every write() system call called by PG really writes > to disk before return)... You'd have to turn that mode on on the data drives as well to get consistency, because fsync=off disables checkpoint fsyncs of the data files as well. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com