[Box Backup] Attributes not backed up correctly, also request to add ACL support

Achim boxbackup at boxbackup.org
Tue Aug 11 23:59:36 BST 2009


Hello Chris:

On 11/08/2009 22:10, Chris Wilson wrote:
>> From your answer "ignore[..] them entirely" I understand that
>> [backing up file attributes under Windows] is not an easy fix,
>> and perhaps not possible at all?
>
> It is possible, but it requires either:
>
> 1. cramming the Windows file attributes into the Unix 9-bit format in
> such a way that restores of Windows files on Unix will have weird
> permissions (we already go to great lengths to avoid restoring files
> with all-zero permissions on Unix which makes them unreadable to anyone
> but root); or
>
> 2. storing Windows files with attributes that are not
> backwards-compatible with old clients or compatible with being restored
> on Unix.

What about the way that Samba achieves this [1] with mapping the 
attributes to the executable bits? The chapter contains also some 
interesting information about ACLs

>> So that user threatens to stop using Box Backup if it gets more
>> accurate at backing up and restoring meta data? Interesting case,
>> would be nice to know the rationale behind that position.
>
> I think he believed that in the case of a bare-metal restore, the
> original permissions would be worthless as the ownership SIDs for each
> ACL entry would have changed. We could look them up by name if the
> original numeric SID didn't exist, or as you say, add a switch to
> restore ACLs explicitly.

Exactly: ACLs are by default off, but can be enabled. In case of 
disaster recover, it is at the discretion of the administrator to 
restore with the original SIDs or leave them out, correcting the 
permissions by hand. I can only see potential upsides here.

Perhaps that user is willing to voice his opinion?

Thanks in advance, Achim

[1] 
<http://us3.samba.org/samba/docs/using_samba/ch08.html#samba2-CHP-8-SECT-2>



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