[Duplicity-talk] duplicity and compressed archives

[Noel Kelly]

Hi

I have been running some tests using duplicity.  I have found that 
compressed archives (eg .tar.gz) do not seem to transfer incrementally 
using librsync.

If I transfer a compressed archive of a database dump using rsync then 
only the changes are transferred after the initial full transfer.

When I try the same experiment using duplicity it simply transfers the 
entire file again.  It is as though librsync is not being called/used.

Below is a copy of my last two duplicity commands - note the 
ChangeFileSize is 51Mb each time.

Any suggestions or explanations much appreciated!

Cheers
Noel



address@hidden:/backups/20091003/$ sudo duplicity --scp-command "scp -l 1024" 
./com.sql.bz2  scp://address@hidden/com/
Password:
GnuPG passphrase:
No signatures found, switching to full backup.
tmpLUSD-P
...
100%   24KB  24.1KB/s   00:00   
--------------[ Backup Statistics ]--------------
StartTime 1254935682.83 (Wed Oct  7 18:14:42 2009)
EndTime 1254936124.95 (Wed Oct  7 18:22:04 2009)
ElapsedTime 442.13 (7 minutes 22.13 seconds)
SourceFiles 1
SourceFileSize 52987804 (50.5 MB)
NewFiles 1
NewFileSize 52987804 (50.5 MB)
DeletedFiles 0
ChangedFiles 0
ChangedFileSize 0 (0 bytes)
ChangedDeltaSize 0 (0 bytes)
DeltaEntries 1
RawDeltaSize 5204480 (4.96 MB)
TotalDestinationSizeChange 53615229 (51.1 MB)
Errors 0
-------------------------------------------------

address@hidden:/backups/20091006/$ sudo duplicity --scp-command "scp -l 1024" 
./com.sql.bz2  scp://address@hidden/com/
Password:
GnuPG passphrase:
duplicity-full.2009-10-07T18:14:34+01:00.manifest.gpg                              
100%  464     0.5KB/s   00:00   
duplicity-full-signatures.2009-10-07T18:14:34+01:00.sigtar.gpg                     
100%   24KB  24.1KB/s   00:01   
tmpxMoIR1
...
 100%   24KB  24.0KB/s   00:01   
--------------[ Backup Statistics ]--------------
StartTime 1254937169.04 (Wed Oct  7 18:39:29 2009)
EndTime 1254937617.68 (Wed Oct  7 18:46:57 2009)
ElapsedTime 448.64 (7 minutes 28.64 seconds)
SourceFiles 1
SourceFileSize 52903512 (50.5 MB)
NewFiles 0
NewFileSize 0 (0 bytes)
DeletedFiles 0
ChangedFiles 1
ChangedFileSize 52903512 (50.5 MB)
ChangedDeltaSize 0 (0 bytes)
DeltaEntries 1
RawDeltaSize 5204480 (4.96 MB)
TotalDestinationSizeChange 53540930 (51.1 MB)
Errors 0
-------------------------------------------------