From owner-freebsd-questions@FreeBSD.ORG Mon Jun 27 09:56:52 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 02EAD1065672 for ; Mon, 27 Jun 2011 09:56:52 +0000 (UTC) (envelope-from ml@my.gd) Received: from mail-wy0-f182.google.com (mail-wy0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id 930E98FC0C for ; Mon, 27 Jun 2011 09:56:50 +0000 (UTC) Received: by wyg24 with SMTP id 24so1740480wyg.13 for ; Mon, 27 Jun 2011 02:56:49 -0700 (PDT) Received: by 10.217.6.197 with SMTP id y47mr2172907wes.55.1309168609852; Mon, 27 Jun 2011 02:56:49 -0700 (PDT) Received: from dfleuriot-at-hi-media.com ([83.167.62.196]) by mx.google.com with ESMTPS id ei4sm3958217wbb.26.2011.06.27.02.56.48 (version=SSLv3 cipher=OTHER); Mon, 27 Jun 2011 02:56:48 -0700 (PDT) Message-ID: <4E0853DF.1080407@my.gd> Date: Mon, 27 Jun 2011 11:56:47 +0200 From: Damien Fleuriot User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.18) Gecko/20110616 Thunderbird/3.1.11 MIME-Version: 1.0 To: Joshua Isom References: <4E06180F.7090409@gmail.com> <16AE025C-EA55-45F3-8419-542228CE5AA4@my.gd> <4E06C2D1.4050601@gmail.com> In-Reply-To: <4E06C2D1.4050601@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "freebsd-questions@freebsd.org" Subject: Re: Performance of a USB ZIL for ZFS X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Jun 2011 09:56:52 -0000 On 6/26/11 7:25 AM, Joshua Isom wrote: > On 6/25/2011 9:32 PM, Damien Fleuriot wrote: >> On 25 Jun 2011, at 19:17, Joshua Isom wrote: >> >>> I was wondering if anyone had tried using a decent USB flash drive >>> for the ZIL. I know it'd be hard finding one fast enough, but some >>> from patriot seem like they might be suitable for home use. Part of >>> the idea is to just minimize hard drive thrashing and the wear and >>> tear associated with it. If it helps prevent the drives from going >>> bad, and doesn't hurt performance too bad all the better. But if >>> it's going to hurt performance too much or not help prevent thrashing >>> there isn't a point. >>> _______________________________________________ >>> freebsd-questions@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >>> To unsubscribe, send any mail to >>> "freebsd-questions-unsubscribe@freebsd.org" >> >> >> I stopped reading at the title. >> The answer is no. >> >> Grab a SSD for $80-120ish. > > > Perhaps it would have helped to read the email. Part of the concern is > making sure the drives don't fail and not just throughput. > > Given that Kingston sells an SATA SSD for $40 that only gets writes at > 30mb/s write, and some USB drives might get up to 20mb/s. If I get two > drives and put them on different controllers, mirrored, I might get > acceptable performance. I may still loose performance, but if my drives > last a year longer, I can probably accept it. I'm ok with loosing some > performance, but I just don't want it dragging down the system. And if > it won't help the drives last longer there's no point. What do you want to do here, data security or performance ? Having a dedicated ZIL is accepted to be a performance concern, more than security. Obviously you'll do as you please, but I'll tell you what: If you're going to play cheap and grab a USB key for your ZIL, don't be surprised when you lose your data and/or experience downtime because your key went boom, or the USB controller hung for a sec and your sync failed. This is data we're talking about, and considering you want a dedicated ZIL this is probably important and/or voluminous data.