New, exciting 3.10 kernel just made it to Fedora 19 updates. One of the new, exciting features is skinny extents, the documentation for which explains that these can be enabled using "btrfstune -x". However, the current version of btrfs-progs in Fedora-updates is not yet new enough to support this option.
btrfs-progs-0.20.rc1.20130917git194aa4a-1.fc19 has been submitted as an update for Fedora 19. https://admin.fedoraproject.org/updates/btrfs-progs-0.20.rc1.20130917git194aa4a-1.fc19
A new git snapshot of btrfs-progs has been pushed to F19 testing. If possible, please re-test these bugs & feel free to close or comment as appropriate. Thanks, -Eric
Package btrfs-progs-0.20.rc1.20130917git194aa4a-1.fc19: * should fix your issue, * was pushed to the Fedora 19 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing btrfs-progs-0.20.rc1.20130917git194aa4a-1.fc19' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2013-17126/btrfs-progs-0.20.rc1.20130917git194aa4a-1.fc19 then log in and leave karma (feedback).
I just enabled the skinny extends on my BTRFS volume and ran a balance to update the old extends. Turns out that this is not a good idea with the current Fedora kernel (3.10.11-200.fc19.x86_64) because the balance seg faults. We should wait until the kernel patch "Btrfs: fix not being able to find skinny extents during relocate" is in the Kernel.
Thanks for testing. As Josef would say, "welcome to using an experimental filesystem." :( (And this was one of my hesitations about plopping new userspace into Fedora, but *shrug* onward through the fog!) FWIW, aee68ee5f5427b91be5b23459993134ca64ecf00 Btrfs: fix not being able to find skinny extents during relocate is in 3.11 -Eric
btrfs-progs-0.20.rc1.20130917git194aa4a-1.fc19 has been pushed to the Fedora 19 stable repository. If problems still persist, please make note of it in this bug report.