Zoinkies Already did, fresh backup server. 2.5 TB blown through in 3 days.
Unfortunately BTRFS became the Boogeyman Filesystem here being blamed for anything backup related. People overhauling their backup systems, deleting entire backup histories, just to get the same issues with EXT4 because they didn't look at the root causes of the issues.
The only thing that can happen with v11 -> v12 on BTRFS is the first new backup cycle being full instead of differential, because of the switch from true subvolume snapshot to hardlink. All other issues have nothing to do with the filesystem.
Unfortunately with EXT4 people won't be able to use automatic filesystem compression anymore (saves disk space), or filesystem management while mounted (raid conversions, shrink, grow, add devices etc) and also won't be able to make a true manual S3 backup of their backups anymore due to the lack of snapshot ability. And on crappy HDD's, like offered by cheap VPS providers, how is it going to detect data corruption?
