From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: Re: Slow writes to SAS drives on LSI mpt2sas HBA Date: Thu, 6 Dec 2012 20:43:38 -0500 Message-ID: <450090F8-2B0F-4B38-AB7C-2154C75043F9@gmail.com> References: <536E46D8-A041-4860-A922-21305CAF5321@gmail.com> <1354572400.4420.66.camel@localhost.localdomain> Mime-Version: 1.0 (Mac OS X Mail 6.2 \(1499\)) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mail-qa0-f53.google.com ([209.85.216.53]:62093 "EHLO mail-qa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754401Ab2LGBnD (ORCPT ); Thu, 6 Dec 2012 20:43:03 -0500 Received: by mail-qa0-f53.google.com with SMTP id a19so91142qad.19 for ; Thu, 06 Dec 2012 17:43:02 -0800 (PST) In-Reply-To: <1354572400.4420.66.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: emilne@redhat.com Cc: linux-scsi@vger.kernel.org Hello Ewan On Dec 3, 2012, at 5:06 PM, Ewan Milne wrote: >> > > It sounds like your drive write cache is disabled, 7200RPM is 120 > revolutions/sec, and you are getting 7747584 / 1024 / 63.59 = ~119 IO/s > I believe the write cache is enabled by default on SATA drives, which > would explain the difference. You were exactly right. Thank you! A quick "sdparm -S -set=WCE " and I was back to where I expected. Thanks again, -Greg