Received: from localhost (unknown [200.46.204.184]) by developer.postgresql.org (Postfix) with ESMTP id 31AB92E0042 for ; Mon, 7 Apr 2008 09:37:52 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 30411-03 for ; Mon, 7 Apr 2008 09:37:38 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from ciao.gmane.org (main.gmane.org [80.91.229.2]) by developer.postgresql.org (Postfix) with ESMTP id 2D3012E0048 for ; Mon, 7 Apr 2008 09:37:46 -0300 (ADT) Received: from list by ciao.gmane.org with local (Exim 4.43) id 1JiqbW-0004gT-L2 for pgsql-performance@postgresql.org; Mon, 07 Apr 2008 12:37:42 +0000 Received: from lara.cc.fer.hr ([161.53.72.113]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 07 Apr 2008 12:37:42 +0000 Received: from ivoras by lara.cc.fer.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 07 Apr 2008 12:37:42 +0000 X-Injected-Via-Gmane: http://gmane.org/ To: pgsql-performance@postgresql.org From: Ivan Voras Subject: Re: Looking for bottleneck during load test Date: Mon, 07 Apr 2008 14:37:32 +0200 Lines: 10 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: lara.cc.fer.hr User-Agent: Thunderbird 2.0.0.6 (X11/20071022) In-Reply-To: X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200804/54 X-Sequence-Number: 29547 Hell, Robert wrote: > We have a PostgreSQL 8.2.7 database (~230 GB) running on a machine with 8 Intel Xeon Cores and 32 GB RAM (64-bit Linux 2.6.18). Data is stored on an EMC² CLARiiON on RAID 1/0 (8 x 146 GB 15k rpm). > When we do random I/O with a small test tool (reading random 8k blocks from big files in 200 threads) on the disk we retrieve data with about 25 MB/s. How do you test random IO? Do you use this utility: http://arctic.org/~dean/randomio/ ? If not, try using it, with same parameters. It might be that the latency is destroying your performance. Do you use NFS or are you accessing the storage as SAN?