From owner-freebsd-questions@FreeBSD.ORG Fri Sep 16 13:36:11 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 9D62E106564A for ; Fri, 16 Sep 2011 13:36:11 +0000 (UTC) (envelope-from terje@elde.net) Received: from keepquiet.net (keepquiet.net [IPv6:2a01:4f8:130:84c1::deaf:babe]) by mx1.freebsd.org (Postfix) with ESMTP id 605678FC0A for ; Fri, 16 Sep 2011 13:36:11 +0000 (UTC) Received: from [46.66.20.205] (46.66.20.205.tmi.telenormobil.no [46.66.20.205]) (using TLSv1 with cipher ECDHE-RSA-AES128-SHA (128/128 bits)) (Client did not present a certificate) (Authenticated sender: terje@elde.net) by keepquiet.net (Postfix) with ESMTPSA id B9D2A2E1C8; Fri, 16 Sep 2011 15:36:06 +0200 (CEST) References: <20110916063153.200375qdq59crf8c@mail.top-consulting.net> In-Reply-To: <20110916063153.200375qdq59crf8c@mail.top-consulting.net> Mime-Version: 1.0 (iPhone Mail 8C148) Content-Type: text/plain; charset=us-ascii Message-Id: <32990703-D068-4B0D-AF3A-C1E6EA0A4100@elde.net> Content-Transfer-Encoding: quoted-printable X-Mailer: iPhone Mail (8C148) From: Terje Elde Date: Fri, 16 Sep 2011 15:35:54 +0200 To: "freebsd@top-consulting.net" Cc: "freebsd-questions@freebsd.org" 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 13:36:11 -0000 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 t= wo pieces. 50 GB for FreeBSD to boot and the rest available to configure as s= torage. ZFS will want to write to it's ZIL (zfs intent log) before writing to the fi= nal location of the data. Even if you're not waiting for the ZIL-write to di= sk (because of the controller ram), those writes will probably make it throu= gh to disk. That gives you twice as many writes to disk, and a lot more seek= .=20 If you want to take zfs for a proper spin, I'd like to sugget adding two sma= ll SSDs to the setup, mirrored by zfs. You can use those both for the ZIL, a= nd 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, b= oth for your benchmark, and real load.=20 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 wor= d for it.=20 Terje=