From owner-freebsd-questions@FreeBSD.ORG Fri Sep 16 13:57:54 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 3C0A8106564A for ; Fri, 16 Sep 2011 13:57:54 +0000 (UTC) (envelope-from freebsd@top-consulting.net) Received: from smtp3.emailarray.com (smtp3.emailarray.com [65.39.216.17]) by mx1.freebsd.org (Postfix) with ESMTP id C7F6F8FC0C for ; Fri, 16 Sep 2011 13:57:53 +0000 (UTC) Received: (qmail 70120 invoked by uid 89); 16 Sep 2011 13:57:52 -0000 Received: from unknown (HELO localhost) (freebsd@top-consulting.net@192.168.1.6) (POLARISLOCAL) by smtp3.emailarray.com with (DHE-RSA-AES256-SHA encrypted) SMTP; 16 Sep 2011 13:57:51 -0000 Received: from modemcable238.94-200-24.mc.videotron.ca (modemcable238.94-200-24.mc.videotron.ca [24.200.94.238]) by mail.top-consulting.net (Horde Framework) with HTTP; Fri, 16 Sep 2011 09:57:45 -0400 Message-ID: <20110916095745.872947fg6vym1vy8@mail.top-consulting.net> Date: Fri, 16 Sep 2011 09:57:45 -0400 From: freebsd@top-consulting.net To: "freebsd-questions@freebsd.org" References: <20110916063153.200375qdq59crf8c@mail.top-consulting.net> <32990703-D068-4B0D-AF3A-C1E6EA0A4100@elde.net> In-Reply-To: <32990703-D068-4B0D-AF3A-C1E6EA0A4100@elde.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes"; format="flowed" Content-Disposition: inline Content-Transfer-Encoding: 7bit User-Agent: Internet Messaging Program (IMP) H3 (4.3.7) X-Originating-IP: 24.200.94.238 X-DSPAM-Result: Innocent X-DSPAM-Processed: Fri Sep 16 09:57:52 2011 X-DSPAM-Confidence: 0.9284 X-DSPAM-Improbability: 1 in 1297 chance of being spam X-DSPAM-Probability: 0.0000 X-DSPAM-Signature: 1,4e7355e011841930556863 X-DSPAM-Factors: 27, net>+>, 0.01000, the+setup, 0.01000, net+wrote, 0.01000, >+two, 0.01000, Note+you, 0.01000, trouble+if, 0.01000, >+On, 0.02929, (because, 0.06134, surprised+if, 0.06134, wrote, 0.06330, to+it's, 0.06950, two+small, 0.08225, in+trouble, 0.08523, up+I, 0.09383, FreeBSD, 0.09467, a+fairly, 0.09656, Subject*Re, 0.09826, setup, 0.09893, at+12, 0.10225, Subject*(, 0.10954, the+raid, 0.11560, >+Note, 0.11560, ?, 0.11976, I+think, 0.12153, but+since, 0.12236, wrote+>>, 0.12814, before+writing, 0.13558 X-PolarisMail-Flags: x Subject: Re: FS of choice for max random iops ( Maildir ) 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: Fri, 16 Sep 2011 13:57:54 -0000 Quoting Terje Elde : > On 16. sep. 2011, at 12:31, freebsd@top-consulting.net wrote: >> Right now I defined an entire array of 8TB ( all 16 disks ) >> separated in two pieces. 50 GB for FreeBSD to boot and the rest >> available to configure as storage. > > ZFS will want to write to it's ZIL (zfs intent log) before writing > to the final location of the data. Even if you're not waiting for > the ZIL-write to disk (because of the controller ram), those writes > will probably make it through to disk. That gives you twice as many > writes to disk, and a lot more seek. > > If you want to take zfs for a proper spin, I'd like to sugget adding > two small SSDs to the setup, mirrored by zfs. You can use those both > for the ZIL, and also as cache, for the array. That's a fairly small > investment these days, and I would be surprised if it didn't > significantly improve performance, both for your benchmark, and real > load. > > Note: you might be in trouble if you loose your ZIL, thus the > doubling up. I *think* you can SSD a cache without risking dataloss, > but don't take my word for it. > > Terje I know it's usually a big no-no but since I have the battery backed-up write cache from the raid card, can't I just disable the ZIL entirely ?