Date: Sat, 26 May 2007 12:30:42 -0700 From: "pete wright" <nomadlogic@gmail.com> To: "Svein Halvor Halvorsen" <svein.h@lvor.halvorsen.cc> Cc: Roland Smith <rsmith@xs4all.nl>, questions@freebsd.org Subject: Re: Restore UFS snapshot Message-ID: <57d710000705261230q74830a87j8228f951119e4b22@mail.gmail.com> In-Reply-To: <465884E3.5000500@lvor.halvorsen.cc> References: <465864F4.7060500@lvor.halvorsen.cc> <20070526180336.GB34660@slackbox.xs4all.nl> <465884E3.5000500@lvor.halvorsen.cc>
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On 5/26/07, Svein Halvor Halvorsen <svein.h@lvor.halvorsen.cc> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Roland Smith wrote: > >> Is it possible to rollback a file system snapshot, i.e. restore the > >> file system to the state it was in at the time a mksnap_ffs command > >> was issued? > > > > You can mount the snapshot, and then copy the files back to the original fs. > > Note that cp can preserve flags, but not ACLs AFAIK. > > > Yes, I know that this is possible. However, it's a lot of work. > There should be some straightforward way of rolling back to a > snapshot, since the files and all the file system structure are > already there. Also, there might not be room on the disk for it. > > well, if you are using snapshot's you already have most likely calculated the overhead that the snapshot(s) will take - so i'm a little confused at to the lack of room available for the snapshot. it's not uncommon to have hourly, daily, weekly snapshot's of given volumes. > >> User scenario: > >> > >> Before a major upgrade (eg. releng->current, portupgrade -a, etc), > >> it would be nice to mksnap_ffs, and then after the upgrade be able > >> to either delete the snapshot if all went well, or rollback to the > >> snapshot. > > > > You should use dump(8) in this case. Create level 0 dumps of your > > filesystems and store them somewhere. You can dump live filesystems with > > dump's -L flag. > > > > If you botch the upgrade, you can use restore(8) to revert your > > filesystems to the situation before the upgrade. > > > > Note that you should really make regular dumps of your filesystems as > > backups anyway! > > This is also beyond the point, although I appreciate that you > suggest alternative ways to meet my objectives. dump/restore would > also require additional disk space. > > I do actually backup my data on a regular basis, but not all of my > computers really need external backup, as I could stand some > downtime. However, if I could easily make a snapshot, and then > either roll back or delete it afterwards, it would be a nice > compromise between security and effort. And also: it seems it should > be possible to do this. If not, I might want to make a tool for it. > > they handbook has a pretty decent example of how to use dump along side mksnap_ffs - and it seems pretty robust to me. when dealing with whole filesystems and important data i think dump(8) is really the way to go as much work has been put into ensuring that you end up with a consistent image on disk. having said that - i see no reason why one couldn't write a wrapper around dump(8) and mksnap_ffs. -p -- ~~o0OO0o~~ Pete Wright www.nycbug.org NYC's *BSD User Group
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