Well, the official btrfs docs call it “incremental”, maybe you want to argue with those guys. :P
For example, here it says:
efficient incremental filesystem mirroring and backup
But yeah, I guess, I wasn’t quite accurate there, because I was conflating it with incremental backups.
Semantically, it’s like you have a full copy in the first snapshot, but because of copy-on-write magic, it doesn’t actually need to duplicate the bytes until the data gets changed for the first time.
Still means, though, that deleting an intermediate snapshot will only free up data, if something’s contained in it, which is reverted in later snapshots.
Send/receive of subvolume changes, efficient incremental filesystem mirroring and backup
This is explicitly talking about a different feature that can incrementally sending changes to the filesystem to another filesystem as a backup. Not at all about how snapshots work.
Well, the official btrfs docs call it “incremental”, maybe you want to argue with those guys. :P
For example, here it says:
But yeah, I guess, I wasn’t quite accurate there, because I was conflating it with incremental backups.
Semantically, it’s like you have a full copy in the first snapshot, but because of copy-on-write magic, it doesn’t actually need to duplicate the bytes until the data gets changed for the first time.
Still means, though, that deleting an intermediate snapshot will only free up data, if something’s contained in it, which is reverted in later snapshots.
You missed an important part of that quote:
This is explicitly talking about a different feature that can incrementally sending changes to the filesystem to another filesystem as a backup. Not at all about how snapshots work.