From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Snook Subject: Re: Performance problems with 3ware 9500S-4LP and 2.6.25-rc3 Date: Wed, 27 Feb 2008 14:55:52 -0500 Message-ID: <47C5C048.9080704@redhat.com> References: <20080226174314.GA30767@skl-net.de> <47C45B80.6090907@redhat.com> <20080227101143.GC30767@skl-net.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([66.187.233.31]:56965 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751814AbYB0T5Q (ORCPT ); Wed, 27 Feb 2008 14:57:16 -0500 In-Reply-To: <20080227101143.GC30767@skl-net.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Andre Noll Cc: adam radford , Tony Battersby , =?ISO-8859-1?Q?Johannes_W=F6rner?= , James Bottomley , linux-scsi , linux-kernel Andre Noll wrote: > On 13:33, Chris Snook wrote: > >>> During the daily cron job that uses rsync to sync a 500G file system >> >from another machine to the raid on the 3ware controller the load >>> jumps up, and the machine becomes sluggish as hell. For example, an >>> ssh login to that machine takes minutes to complete and ldap becomes >>> unreliable while the rsync job is running. Even Nagios complains >>> about the machine being down while rsync is running. >> You're putting your box under astronomical load. This is generally >> regarded as a bad idea, regardless of how well your storage controller >> is performing. > > The machine becomes sluggish also when I write directly to the raid > array. A simple > > dd if=/dev/zero of=tmpfile > > shouldn't push the load up to 4, right? Actually, it's normal for pdflush to spawn up to 8 threads when you're dirtying memory faster than it can be written to disk. Load going to 4 is not abnormal. ssh logins taking minutes is very abnormal. >> Can you measure the single-threaded throughput (say, >> coping one huge file, and then syncing) to give us a baseline >> performance figure? > > Single threaded throughput seems to be ok (140M/s). The problem is > that the machine becomes unresponsive. Does the machine become unresponsive during the single-threaded test, or only when doing the rsync? -- Chris