[Sugar-devel] [PATCH] Journal Volumes Backup and Restore

[James Cameron]

On Mon, Jun 28, 2010 at 05:21:39PM -0400, Martin Abente wrote:
> On Mon, 28 Jun 2010 16:13:33 -0400, Martin Langhoff
> <martin.langhoff at gmail.com> wrote:
> > On Mon, Jun 28, 2010 at 3:58 PM, Martin Abente
> > <mabente at paraguayeduca.org> wrote:
> >> Well, originally I added a XS backup and restore option (Journal
> >> Management) into the Control Panel. Even when it was not intended for
> >> upstreaming, I sent it to the mailing list, therefore a discussion
> >> started
> >> about where these backup and restore options should go. Finally, this
> >> idea
> >> of having the options in the resouces (volumes) palette was the most
> >> wanted.
> > 
> > By whom? ... what is the scenario where you need to click on the backup
> > button?
> > 
> 
> The ones that replied to the previous emails sent by Esteban Arias a few
> months ago, James Cameron, Bernie and myself.
> http://lists.sugarlabs.org/archive/sugar-devel/2010-April/023273.html

My expectation was that the child user would use backup daily, or more
frequently, and a full restore only if a laptop was reimaged or all
content was lost.

> >> Not yet, it does a full restore from the one that is available on the
> >> storage device.
> > 
> > What worries me with this is that it _destroys anything done since the
> > last backup_.
> 
> Yes, it is a problem to loose _some_ data. But it is a bigger problem to
> not being able to backup and restore, loosing _all_ data. For now this is
> the state of the art :)

I may not understand the design yet.

To lose all data sounds simple; child does backup of empty journal, child
fills journal with valuable content, child does restore.  Result empty
journal?

I think that could be solved by a merge restore.  This is just for
discussion, I'm not offering code or suggesting you defer your work just
for this.

Merge restore logic would be:

for each item in backup
    if item is not in journal
        attempt to restore it

Failure to proceed due to lack of disk space should be handled; by
advising the user that there is not enough available space to restore
the whole backup, and that only a portion of the backup was restored.

Being able to view the backup content in the journal would allow per
item restore.

-- 
James Cameron
http://quozl.linux.org.au/