From owner-freebsd-scsi@FreeBSD.ORG Wed May 21 19:46:26 2008 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 32EC2106566B for ; Wed, 21 May 2008 19:46:26 +0000 (UTC) (envelope-from cdillon@wolves.k12.mo.us) Received: from mail.wolves.k12.mo.us (mail.wolves.k12.mo.us [207.160.214.1]) by mx1.freebsd.org (Postfix) with ESMTP id 0530D8FC18 for ; Wed, 21 May 2008 19:46:25 +0000 (UTC) (envelope-from cdillon@wolves.k12.mo.us) Received: from localhost (localhost [127.0.0.1]) by mail.wolves.k12.mo.us (Postfix) with ESMTP id 8BF83B82F; Wed, 21 May 2008 14:30:52 -0500 (CDT) X-Virus-Scanned: amavisd-new at wolves.k12.mo.us Received: from mail.wolves.k12.mo.us ([127.0.0.1]) by localhost (mail.wolves.k12.mo.us [127.0.0.1]) (amavisd-new, port 10024) with LMTP id AT0Fs3zyfZcf; Wed, 21 May 2008 14:30:51 -0500 (CDT) Received: from wolves.k12.mo.us (mail.wolves.k12.mo.us [207.160.214.1]) by mail.wolves.k12.mo.us (Postfix) with ESMTP id 52FB4B820; Wed, 21 May 2008 14:30:51 -0500 (CDT) Received: from rstech21.int.wolves.k12.mo.us (rstech21.int.wolves.k12.mo.us [10.1.3.201]) by www.wolves.k12.mo.us (Horde Framework) with HTTP; Wed, 21 May 2008 14:30:51 -0500 Message-ID: <20080521143051.17771kseoxrlhy7f@www.wolves.k12.mo.us> Date: Wed, 21 May 2008 14:30:51 -0500 From: Chris Dillon To: Scott Long References: <4832C397.3090004@calorieking.com> <4832E0EE.3030402@samsco.org> <4832E6C2.7040205@calorieking.com> <48336EA0.3050109@samsco.org> In-Reply-To: <48336EA0.3050109@samsco.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes"; format="flowed" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable User-Agent: Internet Messaging Program (IMP) H3 (4.2-RC2) / FreeBSD-6.3 Cc: freebsd-scsi@freebsd.org Subject: Re: Very poor performance from Dell/LSI Logic SAS 3000 series SATA/SAS RAID controller FreeBSD 6.3 X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 May 2008 19:46:26 -0000 Quoting Scott Long : > For data reliability, you really don't want it enabled by default. The > problem is that SATA/ATA performs so poorly without it that everyone > turns it on and lives with the consequences. The tweak that I > recommended puts it in line with what the FreeBSD ATA driver has been > doing for years. Doesn't SATA NCQ solve this particular performance vs. reliability =20 problem since it safely allows multiple outstanding write requests? =20 Of course that means the SATA RAID controller would have to use NCQ on =20 the drives and would probably also need its own non-volatile cache. =20 I've always assumed this is how SCSI/SAS drives (with TCQ) perform as =20 well as they do without sacrificing data integrity. We recently bought a new HP DL380G5 server with a P800 SAS RAID =20 controller, MSA60 external drive shelf with 12 750GB SATA drives, =20 11-drive RAID5 array w/ hot-spare (a few too many drives in a single =20 RAID5 array, I know, but I'm experimenting). The system is running =20 Windows Server 2K3 R2. Without telling the P800 to enable the SATA WC =20 (it has an option to do so, off by default), when doing a drag and =20 drop file copy of several very large files from the internal SAS array =20 to the external SATA array it writes 300MB/sec. I briefly enabled the =20 "Physical Drive Write Cache" on the controller just a few minutes ago =20 and ran another test and didn't notice any difference in write speed. =20 I can only assume from this that the P800 is using NCQ on the SATA =20 drives. --=20 Chris Dillon - NetEng/SysAdm Reeds Spring R-IV School District Technology Department 175 Elementary Rd. Reeds Spring, MO 65737 Voice: 417-272-8266 Fax: 417-272-0015