From owner-freebsd-fs@FreeBSD.ORG Thu Dec 11 17:53:54 2008 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7F062106564A for ; Thu, 11 Dec 2008 17:53:54 +0000 (UTC) (envelope-from uspoerlein@gmail.com) Received: from acme.spoerlein.net (cl-43.dus-01.de.sixxs.net [IPv6:2a01:198:200:2a::2]) by mx1.freebsd.org (Postfix) with ESMTP id 109248FC08 for ; Thu, 11 Dec 2008 17:53:53 +0000 (UTC) (envelope-from uspoerlein@gmail.com) Received: from roadrunner.spoerlein.net (e180183203.adsl.alicedsl.de [85.180.183.203]) by acme.spoerlein.net (8.14.2/8.14.2) with ESMTP id mBBHrp4O075265 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 11 Dec 2008 18:53:52 +0100 (CET) (envelope-from uspoerlein@gmail.com) Received: from roadrunner.spoerlein.net (localhost [127.0.0.1]) by roadrunner.spoerlein.net (8.14.3/8.14.3) with ESMTP id mBBHroL4003105 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 11 Dec 2008 18:53:50 +0100 (CET) (envelope-from uspoerlein@gmail.com) Received: (from uqs@localhost) by roadrunner.spoerlein.net (8.14.3/8.14.3/Submit) id mBBHro2n003104 for freebsd-fs@freebsd.org; Thu, 11 Dec 2008 18:53:50 +0100 (CET) (envelope-from uspoerlein@gmail.com) Date: Thu, 11 Dec 2008 18:53:49 +0100 From: Ulrich Spoerlein To: freebsd-fs@freebsd.org Message-ID: <20081211175349.GA2735@roadrunner.spoerlein.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Subject: ZFS backup advice X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Dec 2008 17:53:54 -0000 Servus, I'm looking for advice on setting up a ZFS based hard disk backup solution. Given a large set of data, with perhaps 500MB data changes per day and two 1 TB disks, which option would you prefer and why: A) Separate ZFS pools on both disk. Using zfs send|recv to transfer snapshots every 2-3 days, taking the "backup" pool offline in the time in between (to keep the disk safe from surges, etc). or B) One ZFS mirror pool across both disk, resilvering the second half every 2-3 days and then detaching it again. Right now I'm favouring option A, as I can selectively "backup" part of the pool (excluding /usr/obj for example, though it is <10% of total capacity, so not a strong point), can use compression on the backup-pool and can potentially keep more snapshots on it than on the live pool. It should also be faster than resilvering the mirror every other day. I'd use B, iff ZFS is able to "self-heal" defective sectors on one mirror half, even if it is not fully resilvered. Does anyone know if this is possible? Please keep me CC'ed. Thanks! Cheers, Ulrich Spoerlein -- It is better to remain silent and be thought a fool, than to speak, and remove all doubt.