[Sugar-devel] Journal Backup/Restore UI
tomeu at tomeuvizoso.net
Sun Mar 28 08:14:21 EDT 2010
I'm a bit confused, is the problem reliable full restore with limited
local space or the DS having the xapian DB open while the copy
happens? Or both?
On Fri, Mar 26, 2010 at 00:51, Bernie Innocenti <bernie at codewiz.org> wrote:
> In Paraguay, we started discussing the topic of improving backup and
> restore procedures. Let's compare notes with a wider audience.
> We started from an existing backup/restore procedure written by Daniel
> Drake one year ago. It's meant to be invoked from the Terminal and uses
> a transactional approach:
> 1) the technician runs a script to restore the journal from the school
> server into a temporary directory while Sugar is still running;
> 2) then, you restart Sugar (by killing the sugar-shell process);
> 3) on startup, the olpc-session script notices the temporary directory
> and replaces the datastore with it almost atomically.
> The problem with this approach was that it only works as long as there's
> a enough free space in the filesystem, which is rarely the case with
> laptops that are actually in use. Transactional behavior would be good
> to have, but I don't see how we could implement it reliably. Even an
> rsync in-place would have to be done with --delete-before to ensure it
> works all the time.
> This opens the question of how we stop the datastore from accessing the
> journal and mess it up while we're still updating it. We're currently
> doing it quite a gross way: kill the datastore process before beginning
> the restore, then restart Sugar:
> We'll thoroughly test this new kludge tomorrow. I'm confident it will
> work, but it's a shame that users need to call tech support in order to
> restore a backup.
> Perhaps it's time to add integrated backup/restore functionality to the
> datastore itself, with a nice UI in the Journal or in the control panel.
> The underlying mechanism could be as simple as the one we're testing
> now, but with proper synchronization with the datastore and no need to
> restart Sugar.
> Shall we go on and write a feature page, targeting 0.90? If it's done as
> a control panel item, it may be sufficiently self-contained to backport
> it all the way back to 0.84.
> For the time being, I might add the backup and restore scripts to
> olpc-utils. Or, better, create a new sugar-utils package for these
> things that are generally useful on any platform.
> // Bernie Innocenti - http://codewiz.org/
> \X/ Sugar Labs - http://sugarlabs.org/
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