From owner-freebsd-fs@FreeBSD.ORG Fri Nov 9 00:22:44 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 2C4AC52D for ; Fri, 9 Nov 2012 00:22:44 +0000 (UTC) (envelope-from prvs=1660defc6c=killing@multiplay.co.uk) Received: from mail1.multiplay.co.uk (mail1.multiplay.co.uk [85.236.96.23]) by mx1.freebsd.org (Postfix) with ESMTP id AEC2F8FC12 for ; Fri, 9 Nov 2012 00:22:43 +0000 (UTC) Received: from r2d2 ([188.220.16.49]) by mail1.multiplay.co.uk (mail1.multiplay.co.uk [85.236.96.23]) (MDaemon PRO v10.0.4) with ESMTP id md50000995205.msg for ; Fri, 09 Nov 2012 00:22:42 +0000 X-Spam-Processed: mail1.multiplay.co.uk, Fri, 09 Nov 2012 00:22:42 +0000 (not processed: message from valid local sender) X-MDRemoteIP: 188.220.16.49 X-Return-Path: prvs=1660defc6c=killing@multiplay.co.uk X-Envelope-From: killing@multiplay.co.uk X-MDaemon-Deliver-To: freebsd-fs@freebsd.org Message-ID: From: "Steven Hartland" To: "Tom Evans" , "FreeBSD FS" References: Subject: Re: SSD recommendations for ZFS cache/log Date: Fri, 9 Nov 2012 00:22:46 -0000 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 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Nov 2012 00:22:44 -0000 ----- Original Message ----- From: "Tom Evans" To: "FreeBSD FS" Sent: Thursday, November 08, 2012 9:07 PM Subject: SSD recommendations for ZFS cache/log > Hi all > > I'm upgrading my home ZFS setup, and want to speed things up a bit by > adding some SSDs for cache/log. I was hoping some more experienced > heads could offer some advice on what I've gleaned so far. > > I've read that the Sandforce based devices get their astonishing write > speeds from compressible data, and that on random data, it is > significantly worse, so comparing headline write speeds is not that > useful. I've also read that MLC flash is significantly slower writing > to the 2nd bit, and so the drive firmware will constantly be moving > bits in the background from 1st bit to 2nd bit, in order to keep high > write speeds, and so the firmware is specially important, which to my > mind rules out devices using stock Sandforce firmware (everyone but > Intel), and OCZ, who I've read too many horror stories about. This is > a home setup, so SLC is out unfortunately. > > Is it still recommended to have a mirror for log device, now that > pools can survive losing a log device unexpectedly? I was planning to > get two 128GB drives, and slice them up 4/8/20/96 for UFS root, swap, > log, cache respectively, but I could instead get a single larger and > faster drive. > > The drives I am thinking of getting are either Intel 330, Intel 520, > Crucial M4 RealSSD or Samsung 830, all in their 120/128GB variants. > Any advice gratefully accepted. New Intel drive announced the other day sounds nice, very much focused on constant timings instead of streaming / random benchmarks. Regards Steve ================================================ This e.mail is private and confidential between Multiplay (UK) Ltd. and the person or entity to whom it is addressed. In the event of misdirection, the recipient is prohibited from using, copying, printing or otherwise disseminating it or any information contained in it. In the event of misdirection, illegible or incomplete transmission please telephone +44 845 868 1337 or return the E.mail to postmaster@multiplay.co.uk.