Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id 217C4B5DBCC for ; Tue, 19 Jul 2011 09:16:29 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.29]) (amavisd-maia, port 10024) with ESMTP id 87532-05 for ; Tue, 19 Jul 2011 12:16:23 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-ew0-f46.google.com (mail-ew0-f46.google.com [209.85.215.46]) by mail.postgresql.org (Postfix) with ESMTP id B8025B5D944 for ; Tue, 19 Jul 2011 09:16:22 -0300 (ADT) Received: by ewy4 with SMTP id 4so1953330ewy.19 for ; Tue, 19 Jul 2011 05:16:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=WOGVkZwvj+jSGdHtVVjbSwVT1imaR0rXT2nvdYyW58E=; b=u+qJOyjbMrUv2bfomv19/8M3WGz8Ls4atnBtzJGWqGDcMAA3TsduGDHUT9xpw65xAK x6d0klDoqsVrx2Fbh+4Z2FivO7JCd2bwUvAsVRHFbbvuw8/9LHkOOqRowA+Yy8cTdjga 0hLrJI1usUvlMHS4pzSXeSZZM9fWOHq9ndPqE= Received: by 10.213.15.69 with SMTP id j5mr294557eba.98.1311077780642; Tue, 19 Jul 2011 05:16:20 -0700 (PDT) Received: from [192.168.73.63] (5357DA75.cm-6-8d.dynamic.ziggo.nl [83.87.218.117]) by mx.google.com with ESMTPS id q56sm2701157eef.49.2011.07.19.05.16.18 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 19 Jul 2011 05:16:19 -0700 (PDT) Message-ID: <4E257587.3040704@gmail.com> Date: Tue, 19 Jul 2011 14:16:07 +0200 From: Yeb Havinga User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.2.18) Gecko/20110616 Lightning/1.0b2 Thunderbird/3.1.11 MIME-Version: 1.0 To: Florian Weimer CC: Andy , pgsql-performance@postgresql.org Subject: Re: BBU still needed with SSD? References: <1310953399.25726.YahooMailClassic@web111304.mail.gq1.yahoo.com> <4E23E72B.2070508@gmail.com> <82vcuyd7p5.fsf@mid.bfk.de> <4E255DF9.20005@gmail.com> <82y5zubl90.fsf@mid.bfk.de> <4E2569B0.2050307@gmail.com> <82livubix4.fsf@mid.bfk.de> In-Reply-To: <82livubix4.fsf@mid.bfk.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.899 tagged_above=-10 required=5 tests=BAYES_00=-1.9, FREEMAIL_FROM=0.001 X-Spam-Level: X-Archive-Number: 201107/194 X-Sequence-Number: 44406 On 2011-07-19 13:37, Florian Weimer wrote: > Is this "Total_LBAs_Written"? I got the same name "Total_LBAs_Written" on an 5.39 smartmontools, which was renamed to 241 Lifetime_Writes_GiB after upgrade to 5.42. Note that this is smartmontools new interpretation of the values, which happen to match with the OCZ tools interpretation (241: SSD Lifetime writes from host Number of bytes written to SSD: 448 G). So for the Intels it's probably also lifetime writes in GB but you'd have to check with an Intel smart values reader to be absolutely sure. > The values appear to be far too low: > > 241 Total_LBAs_Written 0x0032 100 100 000 Old_age Always - 188276 > 242 Total_LBAs_Read 0x0032 100 100 000 Old_age Always - 116800 > > 241 Total_LBAs_Written 0x0032 100 100 000 Old_age Always - 189677 > 242 Total_LBAs_Read 0x0032 100 100 000 Old_age Always - 92509 Hmm that would mean 188TB written. Does that value seem right to your use case? If you'd write 100MB/s sustained, it would take 22 days to reach 188TB. > The second set of numbers are from the drive which wears more quickly. It's strange that there's such a large difference in lifetime left, when lifetime writes are so similar. Maybe there are more small md metadata updates on the second disk, but without digging into md's internals it's impossible to say anything constructive about it. Off-topic: new cool tool in smartmontools-5.4x: /usr/sbin/update-smart-drivedb :-) -- Yeb Havinga http://www.mgrid.net/ Mastering Medical Data