Gzipped files NOT backed up by differential incremental backup.

[Wile_E__Coyote]

On day 1, a data file is created. It is backed up by the daily incremental backup.

On day 4, that same data file is compressed with gzip. It is SKIPPED by that night's incremental backup!

The gzipped version of the file is not backed up until the weekly full backup!

I know why: The modification time on the file is not changed by gzip. Netbackup goes by inode and modification time.

Can Netbackup be instructed to backup files if they're renamed? What other options do I have?

[Will_Restore]

See this old technote on the subject

http://www.symantec.com/business/support/index?page=content&id=TECH52319

Answer/Resolution
NetBackup is operating as designed, but there are two ways to change this behavior so that compressed files do get backed up in this situation.  

It is possible to set up TIR (True Image Restore) backups so that the files will always be backed up, even with regards to the most minor changes.

An alternative to using TIR is to add the following settings to the client's bp.conf file:

USE_CTIME_FOR_INCREMENTALS
DO_NOT_RESET_FILE_ACCESS_TIME

These settings are explained in further detail in the System Administrator's Guide, Volume 2

[Nicolai]

The TIR option is designed for this purpose. It just a checkmark away in the policy definition :)

http://www.symantec.com/docs/HOWTO34490