[Box Backup] Mailbox backup is dangerous.

[Achim]

Hello Christian:

On Thu, 27 Aug 2009 18:00:53 +0200, Christian Tschabuschnig
<tschaboo@gmx.at> wrote:
> Achim wrote:
>> 2. The week after, the user unknowingly overwrites some of the holiday
>> photos from step 1. without noticing: the digital camera re-uses the
same
>> filenames for different photos from a visit to the zoo!
> 
> Your special scenario would be even problematic if bb _would_ work as
> expected since your files wouldn't be recognized as being deleted but as
> being changed (*), so the "old version" will disappear somewhen.

I thought that the "Restore to a certain point in time" was supposed to
solve this issue. Perhaps this would be cleaner with real snapshots, but I
would still expect Boxi to restore the pictures in a version before and
after the overwriting (given of course that a succesful backup took place
in between).

> Although, as Tom already mentioned, this will (with or without this bug)
> only happen when you reach the softlimit and the housekeeping process
> runs. As long as you're far away from that limit and you have enough
> space you shouldn't have to worry. That's how I understood it.

At the same time, this means that you have to set the softlimit way high
to be on the safe side. BB should probably advise the user before it
deletes *anything* from the store.

> So your problem is independent of this bug. What we worry about is the
> following: Housekeeping tries to throw away the oldest stuff first. If
> it has about 100 revisions of 1 spreadsheet it removes the older one
> first. But if you delete a file which has not changed for ages that file
> is "old" for boxbackup anyway and it will be among the very first files
> that housekeeping will delete.

Which is of course a terrible design choice IMHO.

> What I (or we, i suspect) want is that bb treats a file deleted on March
> 1st the same way as a revision of a file which was changed last on March
> 1st. So it stays as long in the storage until there is so much history
> to keep from 2nd March onwards that there is just no space for older
stuff.

Completely agree: thanks for making that clear. This is in fact how I
would have expected BB to behave in the first place.