On Sat, Apr 13, 2019 at 7:08 PM Felix Miata <mrma...@earthlink.net> wrote: > > Anders Andersson composed on 2019-04-13 17:31 (UTC+0200): > > > Felix Miata wrote: > > >> Because of its snapshotting, BTRFS requires considerably more space than > >> older > >> filesystems, as much as double. > > > A btrfs snapshot takes approximately zero space. Where did you get > > this idea from? > > (not an exhaustive list) > > 1: "Disk Space Full Because of Snapper" on https://en.opensuse.org/SDB:BTRFS > > 2: Since 2015, BTRFS has been the default / filesystem on openSUSE, which > recommends minimum / filesystem size of 20GB for EXT4, compared to 40GB for > BTRFS. > > 3: Much more common / filesystem freespace exhausted threads on mailing lists > and > web forums from BTRFS users compared to EXT4 users, with the usual > recommendation > to delete one or more snapshots to free space. > > 4: > https://btrfs.wiki.kernel.org/index.php/FAQ#Help.21_I_ran_out_of_disk_space.21 > > 5: > https://btrfs.wiki.kernel.org/index.php/FAQ#Why_is_free_space_so_complicated.3F > > 6: > https://www.linuxquestions.org/questions/linux-containers-122/docker-on-btrfs-using-much-space-in-var-lib-docker-btrfs-4175622037/#post5811463
Of course you will run out of space if you keep taking snapshots! Btrfs never does this, but you can do it *manually* or with third-party tools. When you take a snapshot, btrfs will keep everything until it's deleted. That's why everyone says that if you run out of space, you can delete snapshots. If the advise to the user is to delete a snapshot, it is something that the user did *because* they wanted to retain those files. The "Snapper" user has *installed* a tool that takes snapshots all the time - obviously you will run out of space because every file you modify or delete will still be stored in its original version until you remove the snapshot.
