Re: [BackupPC-users] Compression level

[John P. <jp...@cl...>]

Rich Rauenzahn wrote:
>
>
> I know backuppc will sometimes need to re-transfer a file (for instance, 
> if it is a 2nd copy in another location.)  I assume it then 
> re-compresses it on the re-transfer, as my understanding is the 
> compression happens as the file is written to disk.(?)  
>
> Would it make sense to add to the enhancement request list the ability 
> to replace the existing file in the pool with the new file contents if 
> the newly compressed/transferred file is smaller?  I assume this could 
> be done during the pool check at the end of the backup... then if some 
> backups use a higher level of compression, the smallest version of the 
> file is always preferred (ok, usually preferred, because the transfer is 
> avoided with rsync if the file is in the same place as before.)
>
> Rich
>
>   
What happens is the newly transfered file is compared against candidates 
in the pool with the same hash value and if one exists it's just 
linked,   The new file is not compressed.   It seems to me that if you 
want to change the compression in the pool the way to go is to modify 
the BackupPC_compressPool script which compresses an uncompressed pool 
to instead re-compress a compressed pool.   There is some juggling that 
goes on to maintain the correct inode in the pool so all the links 
remain valid and this script already does that. 

John