From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Subject: Re: [linux-lvm] Keep snapshots active for 24 hours? Message-ID: <20011214153614.A855@lynx.no> References: <20011214113804.I940@lynx.no> Mime-Version: 1.0 Content-Disposition: inline In-Reply-To: ; from steve.wray@the.net.nz on Sat, Dec 15, 2001 at 10:52:17AM +1300 Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: Date: Fri Dec 14 16:34:02 2001 List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-lvm@sistina.com On Dec 15, 2001 10:52 +1300, Steve Wray wrote: > I'd been wondering if snapshotting could be used for; > > - providing 'virtual journalling' any filesystem that happens to > be on a logical volume. It could, but you would have to make a _lot_ of snapshots for it to be worthwhile (i.e. one every 10-30 seconds or so). If you want this for "non-journaled" filesystems, you can use the ext3 journaling code to add this to most any block based filesystem. It isn't trivial, but at least possible. > - take a snapshot, install something or try something out > that might break something, then restore *directly* from > the snapshot if anything goes wrong; without having to actually > back it up to media and restore it. Yes, this would be clever. I'd rather that RPM/DEB package tools just become smarter (like AIX LPP) where it allows you arbitrary amounts of back-out from updated packages (as long as you have enough disk space). After you have "applied" a package, you can test it out, and either commit it or revert to the old version. The rpm and dpkg tools could just do this by checksumming any existing files from the previous install and only backing up those that had changed between versions. Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/