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( [81.208.31.211]) by mx.google.com with ESMTPS id y6sm42237546mug.1.2008.04.18.07.38.06 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 18 Apr 2008 07:38:07 -0700 (PDT) Cc: Matthew , pgsql-performance@postgresql.org Message-Id: <544D07A2-EB3F-4D91-A749-0C4D5D38AB80@gmail.com> From: Enrico Sirola To: Craig Ringer In-Reply-To: <47FFA7FF.10801@postnewspapers.com.au> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v919.2) Subject: Re: Performance increase with elevator=deadline Date: Fri, 18 Apr 2008 16:38:05 +0200 References: <47FFA7FF.10801@postnewspapers.com.au> X-Mailer: Apple Mail (2.919.2) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=1.094 tagged_above=0 required=5 tests=AWL=-1.094, RCVD_IN_BL_SPAMCOP_NET=2.188 X-Spam-Level: * X-Archive-Number: 200804/268 X-Sequence-Number: 29761 Hi, Il giorno 11/apr/08, alle ore 20:03, Craig Ringer ha scritto: > > Speaking of I/O performance with PostgreSQL, has anybody here done > any testing to compare results with LVM to results with the same > filesystem on a conventionally partitioned or raw volume? I'd > probably use LVM even at a performance cost because of its admin > benefits, but I'd be curious if there is any known cost for use with > Pg. I've never been able to measure one with other workloads. I performed some tests some time ago. LVM is significantly slower. The disk subsystem is a HP P400/512MB battery-backed controller with 4 disks in raid 10. See the tests: ext3 tests: bonnie++ -s 16000 -u 0 -f -b = = = = = = = ======================================================================== Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP 16000M 153637 50 78895 17 204124 17 700.6 1 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 2233 10 +++++ +++ 2606 8 2255 10 +++++ ++ + 2584 7 16000M,,,153637,50,78895,17,,,204124,17,700.6,1,16,2233,10,+++++,+++, 2606,8,2255,10,+++++,+++,2584,7 bonnie++ -s 16000 -u 0 -f = = = = = = = ======================================================================== Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP 16000M 162223 51 77277 17 207055 17 765.3 1 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ 16000M,,,162223,51,77277,17,,,207055,17,765.3,1,16,+++++,+++,+++++,+++, +++++,+++,+++++,+++,+++++,+++,+++++,+++ = = = = = = = ======================================================================== LVM tests: bonnie++ -u 0 -f -s 16000 -b Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP 16000M 153768 52 53420 13 177414 15 699.8 1 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 2158 9 +++++ +++ 2490 7 2177 9 +++++ ++ + 2460 7 16000M,,,153768,52,53420,13,,,177414,15,699.8,1,16,2158,9,+++++,+++, 2490,7,2177,9,+++++,+++,2460,7 bonnie++ -u 0 -f -s 16000 Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP 16000M 161476 53 54904 13 171693 14 774.3 1 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ 16000M,,,161476,53,54904,13,,,171693,14,774.3,1,16,+++++,+++,+++++,+++, +++++,+++,+++++,+++,+++++,+++,+++++,+++ Bye, e.