Size of differential backups in production environments

[Ty! Boyack]

Folks,

I'm trying to get an idea of what size incrementals are generated with
rdiff-backup.  Granted that this number will vary GREATLY with the
type of data being backed up and types of use, but I'd like to get
some numbers from people using this in production.

As an example, on our systems, we run user home directories and
ecological research data directories with traditional file-date-based
incremental daily tape backups.  On average, we see 4% of our data
change per day.  So, for every GB of disk storage, we need 40M of
backup space for that day's incrementals.  I'm hoping that with
rdiff-backup's ability to store binary diff files, we'll see a much
smaller percentage.

I'd appreciate any info on what size of filesystem you are backing up,
how frequent your incrementals are, how big your incremtals are, and
what type of data is being backed up.

Also, if anyone has had experience with this project on large
filesystems, I'd love to chat outside of the list.  We're looking at
using this on around 2TB of data.

Thanks for any help!

-Ty!

-- 
-===========================-
  Ty! Boyack
  NREL Unix Network Manager
  ty@nrel.colostate.edu
  (970) 491-1186
-===========================-