On Sun, Oct 14, 2018 at 04:35:53PM -0600, Chris Murphy wrote: [..] > Ha! I just realized after all this time that the Btrfs wiki does not > make clear how to make a sprout, even though it mentions the more > esoteric recursive seed.[1] Of course you can mkfs.btrfs, mount it, > and send/receive. But send requires read only snapshots. Making a > sprout is easier, you just remove the seed device. This is supported > since 2009. > > # losetup -r /dev/loop0 root.img > # mount /dev/loop0 /mnt/ > # btrfs device add /dev/sda3 /mnt > # mount -o remount,rw /mnt > # btrfs device remove /dev/loop0 /mnt > > And now it replicates extents from seed to sprout. The copy is faster > than pvmove, rsync, dd, or rpm-ostree deploy. This sounds great! I just tried it (on Fedora 29), but those steps don't work for me: # cryptsetup --readonly luksOpen /dev/nbd0p4 tmp # mount -o noatime /dev/mapper/tmp /mnt/tmp # mount: /mnt/tmp: WARNING: device write-protected, mounted read-only. # btrfs device add /dev/nbd1 /mnt/tmp Performing full device TRIM /dev/nbd1 (4.00GiB) ... ERROR: error adding device '/dev/nbd1': Read-only file system Am I missing something? Best regards Georg -- 'NEVER USE A GNUPG VERSION YOU JUST DOWNLOADED TO CHECK THE INTEGRITY OF THE SOURCE - USE AN EXISTING GNUPG INSTALLATION!' (http://lists.gnupg.org/pipermail/gnupg-announce/2006q4/000239.html) _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx