where’s the [any] key?

I’ve been running BackupPC as a backup solution at my work for quite some time now and realized that compression wasn’t enabled by default. To enable it, you need to modify /etc/backuppc/config.pl and change the line…

$Conf{CompressLevel} = 0;

…to any number between 0 (no compression) and 9 (highest compression). Be careful not to set it too high as the higher you go, the more CPU time it requires. Restart BackupPC service either through the web console or by restarting through “/etc/init.d/backuppc restart”. The next time a backup job runs for your hosts, it will run with the compression level you chose.

Here’s an excerpt from BackupPC’s documentation regarding enabling compression:

“Changing compression on or off after backups have already been done will require both compressed and uncompressed pool files to be stored. This will increase the pool storage requirements, at least until all the old backups expire and are deleted.

It is ok to change the compression value (from one non-zero value to another non-zero value) after dumps are already done.  Since BackupPC matches pool files by comparing the uncompressed versions, it will still correctly match new incoming files against existing pool files.  The new compression level will take effect only for new files that are newly compressed and added to the pool.

If compression was off and you are enabling compression for the first time you can use the BackupPC_compressPool utility to compress the pool.  This avoids having the pool grow to accommodate both compressed and uncompressed backups.”

Unfortunately for me, I had to compress my existing pool of a little over 4TB before I could run any new compressed backup jobs. I didn’t have the space to retain both uncompressed and compressed pools. It took close to 200 hours to compress the entire pool, but it was well worth the wait. I had gone from having 300GB to 1.3TB of free space after it was all done.

One last note:  compression needs the Compress::Zlib perl library.  If the Compress::Zlib library can’t be found then $Conf{CompressLevel} is forced to 0 (compression off).

BackupPC: Open Source Backup to disk