From owner-freebsd-scsi@FreeBSD.ORG Tue Sep 2 15:07:48 2014 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id B37B1691 for ; Tue, 2 Sep 2014 15:07:48 +0000 (UTC) Received: from smtp1.multiplay.co.uk (smtp1.multiplay.co.uk [85.236.96.35]) by mx1.freebsd.org (Postfix) with ESMTP id 766851353 for ; Tue, 2 Sep 2014 15:07:47 +0000 (UTC) Received: by smtp1.multiplay.co.uk (Postfix, from userid 65534) id 2097420E7088F; Tue, 2 Sep 2014 15:07:46 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.multiplay.co.uk X-Spam-Level: ** X-Spam-Status: No, score=2.2 required=8.0 tests=AWL,BAYES_00,DOS_OE_TO_MX, FSL_HELO_NON_FQDN_1,RDNS_DYNAMIC,STOX_REPLY_TYPE autolearn=no version=3.3.1 Received: from r2d2 (82-69-141-170.dsl.in-addr.zen.co.uk [82.69.141.170]) by smtp1.multiplay.co.uk (Postfix) with ESMTPS id C2DA320E7088C; Tue, 2 Sep 2014 15:07:44 +0000 (UTC) Message-ID: <14D38CFE3887426D9065E26F50457F30@multiplay.co.uk> From: "Steven Hartland" To: "Borja Marcos" References: <93D764A8-01AE-42FA-8020-65CEB6C7D64C@sarenet.es> Subject: Re: Samsung 840 Pro SSD and quirks Date: Tue, 2 Sep 2014 16:07:45 +0100 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 Cc: FreeBSD-scsi X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 02 Sep 2014 15:07:48 -0000 Thanks for the confirmation Borja I was a little confused why our two results differed. For a 12 disk system you'll likely need two SAS2 controllers, or at least 12 SAS lines otherwise you will hit controller throughput issues as a 840 can pretty much saturate a single SAS2 lane on its own. At that point you'll also start to see other issues. I'd strongly suggest moving to stable/10, if you haven't already, particularly if you have large amount of RAM in the system otherwise you will become CPU bound on ARC hash lookups. Regards Steve ----- Original Message ----- From: "Borja Marcos" To: "Steven Hartland" Cc: "FreeBSD-scsi" Sent: Tuesday, September 02, 2014 3:48 PM Subject: Re: Samsung 840 Pro SSD and quirks On Sep 1, 2014, at 5:44 PM, Steven Hartland wrote: > We saw a noticable performance increase on 4k on our 8TB 840 > array but I too couldn't find any concrete information either. > > If anyone has this info and can confirm either way that would > be great. I stand corrected. I have done some benchmarks with just two Samsung SSDs (zpool with two disks, no mirroring) and indeed I get better performance with 4 KB blocks. I did my original tests with 12 disks and some other bottleneck was hiding the performance difference. In both cases, anyway, Trim was working unless the system lies. Thanks!