Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id D6FDE65015E for ; Tue, 12 Aug 2008 21:57:06 -0300 (ADT) Received: from postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 75832-04-7 for ; Tue, 12 Aug 2008 21:56:46 -0300 (ADT) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from wf-out-1314.google.com (wf-out-1314.google.com [209.85.200.172]) by postgresql.org (Postfix) with ESMTP id DB2DB65044C for ; Tue, 12 Aug 2008 21:48:05 -0300 (ADT) Received: by wf-out-1314.google.com with SMTP id 25so2488910wfc.28 for ; Tue, 12 Aug 2008 17:48:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=e1KeN0GoLfOCIqRctcMUrLHkYI8Pjr9kwekFzfRreZY=; b=N8kmLQov/kMpWNBGhs+hv3XV+EsqiE0Fmcslf25t01N+4RjKqr5yEN4IlK8Y4UU+CK 5d7+1lF+nHhDTl8nHbsQp6Dau5yoXRCzXL5SD8Te7F2AMsy8cMNWDApICu3SiNjjZ9xp mfI+MMJn9pjDLQibGcogzKdg8T4eLpQb/65pY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=GttAXvbXnM5BWbtptlEABPabqC+U6OVdYBqWWkoeLzskUAk09Li4hJ+HBGGqWOpbmD MtGNRm8iZfl0bZyv3Cwl23vd2XtPiPoHFr54elZ4zeWz9MjIMqqNYVueFLd4YxPQNg8L qmtNUtAy7EFR0vwZ4y6Mp60j70t21x8yWc8bI= Received: by 10.142.253.21 with SMTP id a21mr2997391wfi.254.1218588484434; Tue, 12 Aug 2008 17:48:04 -0700 (PDT) Received: by 10.142.165.13 with HTTP; Tue, 12 Aug 2008 17:48:04 -0700 (PDT) Message-ID: Date: Tue, 12 Aug 2008 18:48:04 -0600 From: "Scott Marlowe" To: "Scott Carey" Subject: Re: Filesystem benchmarking for pg 8.3.3 server Cc: "Ron Mayer" , "Greg Smith" , Henrik , pgsql-performance@postgresql.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <32A7A76B-16CA-4CDB-AD43-973AD6A3FC7B@mac.se> <48A2050D.4050803@cheapcomplexdevices.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200808/141 X-Sequence-Number: 31022 On Tue, Aug 12, 2008 at 6:23 PM, Scott Carey wrote: > Some SATA drives were known to not flush their cache when told to. > Some file systems don't know about this (UFS, older linux kernels, etc). > > So yes, if your OS / File System / Controller card combo properly sends the > write cache flush command, and the drive is not a flawed one, all is well. > Most should, not all do. Any one of those bits along the chain can > potentially be disk write cache unsafe. I can attest to the 2.4 kernel not being able to guarantee fsync on IDE drives. And to the LSI megaraid SCSI controllers of the era surviving numerous power off tests.