Bacula: To GZIP or Not To GZIP

[ewhac]

I just got Bacula working inside an iocage jail on my FreeNAS box (and boy are my arms tired). When defining FileSets to be backed up, one has the option of specifying compression to be used on a file-by-file basis: GZIP, LZO, or nothing.

I created a dataset to contain the backup volumes, enabled LZ4 compression on it, and nullfs-mounted it inside the jail. So, technically, any data written to that dataset is already being compressed, so I chose to not specify any compression in the Bacula FileSet, out of concern they would have a fight and burn up CPU for no significant gain.

Question: Is there any advantage to be gained by applying GZIP or LZO compression on top of the dataset's LZ4? Is there an optimum combination?

 

[garm]

ZFS will only compress what is compressebla. So if you start writing a compressed archive, wich is basically completely random in the eyes of the filesystem, ZFS will detect that and stop attempting compression.