Date: Wed, 18 Apr 2001 12:16:09 -0500 (CDT) From: Chris Dillon <cdillon@wolves.k12.mo.us> To: Mike Meyer <mwm@mired.org> Cc: Rick Duvall <maillist@coastsight.com>, <questions@FreeBSD.ORG> Subject: Re: Backup and Verify Message-ID: <Pine.BSF.4.32.0104181152200.40930-100000@mail.wolves.k12.mo.us> In-Reply-To: <15069.13630.549850.806893@guru.mired.org>
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On Wed, 18 Apr 2001, Mike Meyer wrote: > You might be able to use vinum to do this for you. The idea is to > mirror your file system, then when you want a backup, take one > mirror offline, backup that mirror, then put it back and let vinum > resync the two drives. You could still catch the file system in > the middle of a transaction, which might or might not be > acceptable. Its not a good idea to just break the mirror and hope you've got what you want on it and in the right order after fsck gets done cleaning up any possible messes. If you just don't want to or can't have things down for an extended period of time (many minutes or even hours) in order to create a clean and consistent backup, then you will have to shut everything down just long enough to get everything on the filesystem in order, sync it up, possibly even re-mount it read-only to get the mark of approval (clean flag) on it, break the mirror, and then bring everything back to life again. At that point you should have a copy of a clean filesystem with all of your databases/etc in a consistent state on the broken mirror, and it only took you a couple of minutes to get it. Ideally, you'd want to use a _third_ mirrored disk for this so that you are always redundant. I'm not sure if Vinum supports mirroring more than two drives, though. Kirk's snapshot code in -current would also be ideal for situations like this. Shut everything down and let all of your services clean up their messes, take a snapshot of the filesystem, bring everything back to life, and then backup the snapshot. Again, a downtime of only a couple of minutes in most cases. If you can't suffer _any_ downtime at all to make a good backup, you've got a whole different class of problem that needs some serious (seriously expensive) hardware and software to solve. -- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net FreeBSD: The fastest and most stable server OS on the planet. For IA32 and Alpha architectures. IA64, PPC, and ARM under development. http://www.freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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