Use --rsyncable gzip optiion

[StevenBarre]

gzip supports an option called --rsyncable that makes the resulting file more deduplication friendly while only costing about 1% additional space. This will allow the NetApp to deduplicate subsequent backups of the same DB if little has changed.

http://smackerelofopinion.blogspot.com/2009/07/rsyncable-gzip.html

https://gist.github.com/ThomDietrich/ca4c7b943f294a4274fbc4e1d68bfb7f