Re: Naming of subvolumes

[Calvin Walton <calvin.walton@kepstin.ca>]

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On Thu, 2012-10-25 at 16:16 +0100, Richard Hughes wrote:
> On Thu, 2012-10-25 at 16:09 +0100, Leonidas Spyropoulos wrote:
> > On another note. How would you implement that logic (make a snapshot
> > before upgrade) without the lib? Would you wrap package manager into a
> > wrapper or patch package manager to call snapshot and the upgrade.
> > In both cases you will need to parse stdout, stderr from the snapshot
> > creation.
> 
> I'm intending to add the snapshot stuff in the logic described here:
> https://gitorious.org/packagekit/packagekit/blobs/master/contrib/systemd-updates/README.txt
> 
> > Also would you automatically roll back to before snapshot if something
> > goes wrong or give option to user? Can you categorise errors on
> > upgrades according ti fatality to the system?
> 
> If *anything* in the upgrade fails and we've already started the package
> transaction then we'd roll back to the previous known-good snapshot.

Rolling back to a previous snapshot would require either a reboot or
using something like rsync to copy the old state back to the currently
mounted subvolume, unfortunately. There's no provision in Linux to allow
switching out the mounted filesystem from under running applications :)
-- 
Calvin Walton <calvin.walton@kepstin.ca>

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