Date: Tue, 23 Nov 2010 15:07:44 -0500 From: "David Magda" <dmagda@ee.ryerson.ca> To: "Mike Tancsa" <mike@sentex.net> Cc: stable@freebsd.org Subject: Re: ZFS backups: retrieving a few files? Message-ID: <8329f4cf52b07aa27a17e8f20369d357.squirrel@webmail.ee.ryerson.ca> In-Reply-To: <4CEC128F.7070903@sentex.net> References: <20101122113541.GA74719@johnny.reilly.home> <4CEA8BA6.7080009@kc8onw.net> <20101122221350.GA81098@johnny.reilly.home> <9F5A7E06-9646-4D3B-BF72-273B713043DE@ee.ryerson.ca> <4CEC128F.7070903@sentex.net>
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On Tue, November 23, 2010 14:14, Mike Tancsa wrote: > I am still trying to figure out the best way to do zfs backups locally > here for rollbacks as well as DR. I was looking at some of the > techniques at > > http://www.cuddletech.com/blog/pivot/entry.php?id=984 > > But thats outdated ? WRT errors in the file, perhaps PAR* tools can > overcome some of these issues if you are dumping to a file on tape > > */usr/ports/archivers/par2cmdline The above is still quite valid, and snapshots are one of base principles of ZFS. From the official ZFS Admin Guide: > The following solutions for saving ZFS data are provided: > * Saving ZFS snapshots and rolling back snapshots, if necessary. > * Saving full and incremental copies of ZFS snapshots and restoring > the snapshots and file systems, if necessary. > * Remotely replicating ZFS file systems by saving and restoring ZFS > snapshots and file systems. > * Saving ZFS data with archive utilities such as tar and cpio or > third-party backup products. http://dlc.sun.com/osol/docs/content/ZFSADMIN/gbchx.html You'll notice that 3/4 mention snapshots. I think them and zfs send/recv are the starting points for getting consistent images of disks. There's no equivalent to dump(8)/restore(8), and so tar and cpio are the main utilities if you want offline stuff: http://www.freebsd.org/doc/handbook/backup-basics.html Until very recently the output format of "zfs send" was not stabilized, so there was no guarantee that it was readable from one version to the next. I believe that has been fixed in [Open]Solaris, but I haven't been tracking pjd's commits that closely to know about FreeBSD. Hopefully "zfs diff" will make it into FreeBSD soon-ish, so that it's easier to do incremental backups to previous snapshots/check points. Traversing large file systems is getting really old in this day-and-age, and that one little thing can certainly remove a lot of I/O seeks if you only want to grab the files that have changed recently. See also the best practice guide, which should be generic enough to cover most operating systems: http://tinyurl.com/2gehn4#Recommendations_for_Saving_ZFS_Data http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide#Recommendations_for_Saving_ZFS_Data -- David Magda Toronto, Canada
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