On 6/3/2011 10:25 AM, Boniforti Flavio wrote:
> Hello there... thanks for all your thoughts and feedbacks...
>
>>> Indeed, the splitting would be OK, but still: I'm in need
>> of backing
>>> up a *big file* which may change in some bytes...
>>
>> Also you have to make sure that that file doesn't change
>> while you are backing/splitting it up otherwise you may be
>> unable to restore it (been there, not pretty trying to
>> recover a corrupted NTFS filesystem).
>
> As far as I know by now is that I'd have to backup with backuppc just
> "copies" of VM images. This should mean that on the other side there is
> already a tool which creates copies of those VM images, thus I shouldn't
> need to care about any corruption at all (it's not my duty).

If they don't change between runs, backuppc will pool the new instance 
with the previous, although a full backup may still take a long time as 
the block checksum verification is done over the whole file.  If they do 
change and you use rsync, only the differences will be transferred (to 
the extent that rsync can find them and resync on the matching parts in 
a huge file), but the server will use the old copy and the differences 
to reconstruct a full-sized copy which is slow and won't be pooled with 
anything else.  If the size and rate of change makes this impractical, 
there are some more efficient approaches you could try that would make 
an intermediate delta-based backup.

-- 
   Les Mikesell
    lesmikesell AT gmail DOT com

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