So I was running a backup with rsync and I saw this:

lib/mysql/ibdata1
        437.40M  33%    4.53MB/s    0:03:10  
inflate returned -3 (0 bytes)
rsync error: error in rsync protocol data stream (code 12) at token.c(557) [receiver=3.1.2]
rsync: connection unexpectedly closed (155602 bytes received so far) [generator]
rsync error: error in rsync protocol data stream (code 12) at io.c(235) [generator=3.1.2]

The issue seems to be that if you’re using rsync compression and the remote file gets changed while the rsync copy is in progress then shit gets corrupted. My solution was to handle error level ’12’ and retry without compression. If the file changes while the rsync is in progress the file will be corrupt, so you shouldn’t rely on the integrity of such files.