From owner-freebsd-current@FreeBSD.ORG Wed Dec 10 21:28:25 2008 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CD7091065670 for ; Wed, 10 Dec 2008 21:28:25 +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 599E28FC25 for ; Wed, 10 Dec 2008 21:28:25 +0000 (UTC) (envelope-from uspoerlein@gmail.com) Received: from roadrunner.spoerlein.net (e180148116.adsl.alicedsl.de [85.180.148.116]) by acme.spoerlein.net (8.14.2/8.14.2) with ESMTP id mBALSNUH018941 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 10 Dec 2008 22:28:24 +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 mBALSMMH007257 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 10 Dec 2008 22:28:22 +0100 (CET) (envelope-from uspoerlein@gmail.com) Received: (from uqs@localhost) by roadrunner.spoerlein.net (8.14.3/8.14.3/Submit) id mBALSLqp007256 for current@freebsd.org; Wed, 10 Dec 2008 22:28:21 +0100 (CET) (envelope-from uspoerlein@gmail.com) Date: Wed, 10 Dec 2008 22:28:21 +0100 From: Ulrich Spoerlein To: current@freebsd.org Message-ID: <20081210212821.GF1494@roadrunner.spoerlein.net> Mail-Followup-To: current@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Cc: Subject: ZFS backup advice X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Dec 2008 21:28:25 -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? Cheers, Ulrich Spoerlein -- It is better to remain silent and be thought a fool, than to speak, and remove all doubt.