From owner-freebsd-stable@FreeBSD.ORG Wed May 21 13:22:46 2008 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7D4F21065672 for ; Wed, 21 May 2008 13:22:46 +0000 (UTC) (envelope-from arnaud.houdelette@tzim.net) Received: from alaranth.tzim.net (alaranth.tzim.net [91.121.97.143]) by mx1.freebsd.org (Postfix) with ESMTP id 39B8E8FC1D for ; Wed, 21 May 2008 13:22:46 +0000 (UTC) (envelope-from arnaud.houdelette@tzim.net) Received: from localhost ([127.0.0.1]) by alaranth.tzim.net with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.69 (FreeBSD)) (envelope-from ) id 1Jynvx-000C2q-Dd for freebsd-stable@freebsd.org; Wed, 21 May 2008 15:00:45 +0200 Message-ID: <48341CF9.3040008@tzim.net> Date: Wed, 21 May 2008 15:00:41 +0200 From: Arnaud Houdelette User-Agent: Thunderbird 2.0.0.14 (Windows/20080421) MIME-Version: 1.0 To: freebsd-stable@freebsd.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-User: tzim@tzim.net X-Authenticator: plain Subject: ZFS on root and disk write caching. X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 May 2008 13:22:46 -0000 I'm playing around with ZFS. Currently, I just use it for storage, with a zpool of 4 sata disks. The system and boot disk is still formatted with UFS. As I'm quite pleased with ZFS features, I'd like to try ZFS on root. The ZFS wiki is quite clear on how to proceed : if the boot and root are on the same disk, you'll have to use bsd labels. The thing is, I read somewhere that ZFS doesn't enable write caching on drives if not used on whole disks. 1. Is it still true on freebsd or just for opensolaris. 2. As the only other(s) label(s) on disk would be the (readonly) boot and swap label, I don't think write caching would be a problem. So how can I tell ZFS it's ok to enable it on the disk (or enable it manualy if necessary and of any use). 3. I'd like to keep the storage pool (zraid1) separated from the system pool (just one disk). The wiki states that we may encounter problems with more than one pool in use : is it still the case ? I know the whole ZFS thing is still experimental, but with it's overall performance, it would really be a shame not to give it its chance. Thanks for your comments. Arnaud Houdelette