From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761944AbYBTAJH (ORCPT ); Tue, 19 Feb 2008 19:09:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753039AbYBTAIz (ORCPT ); Tue, 19 Feb 2008 19:08:55 -0500 Received: from web35715.mail.mud.yahoo.com ([66.163.179.169]:29370 "HELO web35715.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753566AbYBTAIy (ORCPT ); Tue, 19 Feb 2008 19:08:54 -0500 X-Greylist: delayed 396 seconds by postgrey-1.27 at vger.kernel.org; Tue, 19 Feb 2008 19:08:54 EST DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID; b=VKbiDC1qYAeD0MWR/GHMHPg4WlwCm1LqvepfstRhjYKE9HW9ApVJaf3ULEhnkNaNtl6vlr9OsRN+eUKK8ChKIDRKGyd8PcVX0JtSL9ZlbpQQPnjGh3pdImPtqLQArCriVri9qbJ3LEU6VE29mb9Pb4OnunfTyy5cdYS/8oJHBCY=; X-YMail-OSG: 29lIF7AVM1l5HrYES4owaOv7unmo6.GtB6tiQCjqg2HEigZQm8B8xthqX4SaLM1tkHP8lQWlu8S4iiBKBBkipH1odZMK8abbCuIuE4gaRZ3H8jBMkgqpXpuC9cqa1g-- Date: Tue, 19 Feb 2008 16:02:13 -0800 (PST) From: Mariella Petrini Subject: Linux and SSD and how to decrease io delay : question, please To: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Message-ID: <847418.75727.qm@web35715.mail.mud.yahoo.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi All, I have been running Linux kernel 2.6.23 with Debian on a 2 CPUs Dual-Core AMD Opteron(tm) Processor 2218. I have been using an SSD drive (MTRON) connected to a raid controller (LSI MegaRAID 8704ELP) to contain data stored on several databases. Each database contains 20,000 files and there are 50 databases total (1,000,000 files distributed across 50 directories on the filesystem on the ssd). The database server uses the databases very "write" intensively. An approximate percentage could be 20% reads versus 80% random writes. No matter which filesystem type is used (I have tried ext3, xfs, jfs, reiserfs) I see every few seconds snapshots (the could last in the worst case up to 200 seconds, depending on the filesystem type) where the iowait on the ssd device goes approximately over 50% (up to 100%) and the database server threads go to wait (get suspended). Is there any Linux kernel parameter or any Linux parameter that could be varied that could help to decrease the time spent to sync all the data to the SSD device ? Thanks in advance for your help, Mariella ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ