[Duplicity-talk] Remote S3 backups not the same size as source?

[Brandon]

I am using “duply”, a simplified front-end program to duplicity. I am backing 
up all contents of a directory, amongst others, /mnt/Data/Email, to an Amazon 
S3 bucket. There are a total of 83 GB in files. However, when I first ran the 
backup operation, it backed up approximately 37 GB and then said it was 
complete. I figured something went wrong so I then ran the backup operation 
(incremental) again and it backed up another 1.2 GB even though I had not 
modified, removed or added any files to the directory to be backed up. I 
thought something might have been interrupting it so I ran it yet again for the 
third time but that and all subsequent backup runs backed up nothing else 
(except the 104 byte accounting file or whatever). It is not backing up any 
more than 38.2 GB of 83 GB of files. I have verified and the number of files in 
the S3 directory, multiplied by 25 MB (the size of each difftar spanning 
archive file), and indeed it has backed up just 38.2 gigabytes.

What gives here? Why is it not backing up all  83GB? Is there some kind of 
compression going on (although it would still be more than 38.2 GB because I 
have most of my content already compressed)? For whatever reason duplicity does 
not seem to be backing everything up and this worries me.

Also, another directory, /mnt/Data/Organized, is 5.1 GB (according to du -hs) 
yet duply/duplicity says source is 4.94 GB. This is extremely close, and may 
just be a matter of accounting and such, and may be correct. However the 
/mnt/Data/Email is off by over 42 gigabytes!

What can I do to remedy this?

Thanks in advance,

Brandon Edward