From owner-freebsd-fs@FreeBSD.ORG Sat Apr 21 01:25:49 2007 Return-Path: X-Original-To: freebsd-fs@freebsd.org Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 2F6B016A400 for ; Sat, 21 Apr 2007 01:25:49 +0000 (UTC) (envelope-from mike@nux.co.uk) Received: from smtp.nildram.co.uk (smtp.nildram.co.uk [195.112.4.54]) by mx1.freebsd.org (Postfix) with ESMTP id EAFC713C4BF for ; Sat, 21 Apr 2007 01:25:48 +0000 (UTC) (envelope-from mike@nux.co.uk) Received: from office.nux.co.uk (unknown [82.133.40.67]) by smtp.nildram.co.uk (Postfix) with ESMTP id 807402B6B5E for ; Sat, 21 Apr 2007 02:25:47 +0100 (BST) Received: (qmail 18226 invoked by uid 2223); 21 Apr 2007 01:25:47 -0000 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 21 Apr 2007 01:25:47 -0000 Date: Sat, 21 Apr 2007 02:25:47 +0100 (BST) From: Mike Wolman X-X-Sender: mike@nux.eros.office To: ticso@cicely.de In-Reply-To: <20070421010734.GD64413@cicely12.cicely.de> Message-ID: <20070421021529.R16230@nux.eros.office> References: <20070420232209.G4559@nux.eros.office> <20070421000029.N4559@nux.eros.office> <20070421000805.GA64413@cicely12.cicely.de> <20070421011716.B4559@nux.eros.office> <20070421010734.GD64413@cicely12.cicely.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-fs@freebsd.org Subject: Re: lazy mirror / live backup 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: Sat, 21 Apr 2007 01:25:49 -0000 On Sat, 21 Apr 2007, Bernd Walter wrote: > On Sat, Apr 21, 2007 at 01:38:31AM +0100, Mike Wolman wrote: >> My only concern is zfs is quite heavy weight (memory wise) compared to >> gmirror and ufs for a simple laptop/desktop setup which you may just want >> to replicate the entire drive and grab the ggatec device and be ready to >> run should anything happen to the machine. > > Yes - that's unfortunately true. > >> Im sure there are other situations where running zfs on the available >> hardware is not an option compared to gmirror - im not sure what the >> recommended amount for freebsd but as far as i can rember the suggested >> about for solaris is 1Gb - comparing to gmirror i think i have run it on a >> machine doing simple home fileserving with 128Mb. > > Ever thought about UFS snapshots backed with rsync? > You get a consitent pseudo image of your running filesystem with > unallocated blocks represented as zeros. > rsync now allows comparing file chunks and copies only differences. > Still every block need to be read, though. Yea i use rsync and snapshots quite a bit, but unfortunately rsync works at the filesystem level so you cant really get a bootable image of the whole device. It would be nice if this could be done without user interaction, ie if the ggatec component of a mirror disappears and reappears gmirror justs gets to work syncing things up. > > vbackup from devel/plan9port stores checksums and allows offering > only different blocks to the other side. > venti - the backing store behind vbackup - allows compression and > single storage of different blocks with same data, which reduces > the required backup capacity very impressive. > My expirience with vbackup is that this mechanism is fast enough > as long as there are no hughe differences. > I'll take a peek as it sounds interesting, Mike.