Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 66CEC650303 for ; Fri, 8 Aug 2008 13:56:43 -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 90845-06 for ; Fri, 8 Aug 2008 13:56:37 -0300 (ADT) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.190]) by postgresql.org (Postfix) with ESMTP id BC8E66500CD for ; Fri, 8 Aug 2008 13:56:16 -0300 (ADT) Received: by nf-out-0910.google.com with SMTP id c7so370807nfi.23 for ; Fri, 08 Aug 2008 09:56:15 -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=WTWI8pz39Cj1MKZsMIGROb9H+/VFiM1PXefwtFC47PQ=; b=Krj6L5yG3ithJ8n5bF7koMmxPCwSa4w827xQGfmcnFodVs9A1o00oY2rmz/kCLqA45 lWydb5Kapf61EB1oCl0+5N6pV7GH8hZ1xDasaP5/mMn682Yzc7Q1EDoUs8ImyU4Eqik6 BZ49fEbgPA13kAPaNqKa1stdERlWT793Kqxoc= 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=IbtVuWQzfPygNzbDD/20uR0gLFGF/VKClo2Poglx5ciI0TT7cDpcNCHpCegeNRgbex ueCYfPI1ls4xhlAYrF0KWW8ZqLlgVPv8f4PoG+ZI3kTUw6Hi3TJ6WCLIQ0jNxZGciEJu 2oNPdlBPaUmA/SNIW9pGHgoL1tsyvVs2ZpD4k= Received: by 10.210.128.5 with SMTP id a5mr5761333ebd.62.1218214575451; Fri, 08 Aug 2008 09:56:15 -0700 (PDT) Received: by 10.210.72.10 with HTTP; Fri, 8 Aug 2008 09:56:15 -0700 (PDT) Message-ID: <70c01d1d0808080956p6edd172dgb0125a64fad19265@mail.gmail.com> Date: Fri, 8 Aug 2008 09:56:15 -0700 From: "Mark Wong" To: "Mark Mielke" Subject: Re: file system and raid performance Cc: "Andrej Ricnik-Bay" , "Scott Marlowe" , "pgsql-performance@postgresql.org" In-Reply-To: <489B727B.6010800@mark.mielke.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <70c01d1d0808042154u7b78d988vac1e461a93b0ba10@mail.gmail.com> <489A3B75.6060004@paradise.net.nz> <489AC2F0.9050907@paradise.net.nz> <489ACC90.9030401@sime.com> <70c01d1d0808071236u36fe5002w833582b036d952e8@mail.gmail.com> <489B727B.6010800@mark.mielke.cc> 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: 200808/75 X-Sequence-Number: 30956 On Thu, Aug 7, 2008 at 3:08 PM, Mark Mielke wrote: > Andrej Ricnik-Bay wrote: > > 2008/8/8 Scott Marlowe : > > > noatime turns off the atime write behaviour. Or did you already know > that and I missed some weird post where noatime somehow managed to > slow down performance? > > > Scott, I'm quite aware of what noatime does ... you didn't miss a post, but > if you look at Mark's graphs on > http://wiki.postgresql.org/wiki/HP_ProLiant_DL380_G5_Tuning_Guide > they pretty much all indicate that (unless I completely misinterpret the > meaning and purpose of the labels), independent of the file-system, > using noatime slows read/writes down (on average) > > That doesn't make sense - if noatime slows things down, then the analysis is > probably wrong. > > Now, modern Linux distributions default to "relatime" - which will only > update access time if the access time is currently less than the update time > or something like this. The effect is that modern Linux distributions do not > benefit from "noatime" as much as they have in the past. In this case, > "noatime" vs default would probably be measuring % noise. Interesting, now how would we see if it is defaulting to "relatime"? Regards, Mark