Btrfs Won't Likely Replace EXT4 As The Default Until Fedora 23
OpenSUSE 13.2 Beta 1 is using Btrfs by default as the first major tier-one Linux distribution using the next-generation file-system along with SUSE Linux Enterprise. Going back several Fedora releases have been feature proposals to ship Btrfs by default, but they never panned out due to an incomplete FSCK implementation and other issues. While Btrfs is doing well these days with plenty of features, the Btrfs user-space tools continue to be updated, and there doesn't seem to be many corruption issues these days, Fedora Linux isn't yet ready to abandon EXT4. Of course, their parent Red Hat, with Red Hat Enterprise Linux 7.0 dropped EXT4 in favor of XFS.
The reason, however, for Fedora apparently not planning to jump to Btrfs with Fedora 22 in H1'2015 comes down to developer time. Josef Bacik, a Btrfs lead developer and part of Facebook's Btrfs crew, commented on a Fedora development discussion about Btrfs by default.
Josef Bacik commented this Sunday morning, "My plan is to push for F23, I'm still wrapping up some balance bugs and some other issues we've found at work and then this will be my next priority. Suse benefits from having a narrow 'supported' criteria, like only use it with lots of space and don't use any of the RAID stuff, plus they have two kernel guys on it and Dave Sterba who is now in charge of btrfs-progs. Fedora unfortunately has me who has Facebook work to do and Eric [Sandeen] who is a professional [file-system] juggler. We will get there, and when we do it will be less painful than its going to be for Suse since they will have fixed it all for us ;)."
Of course, Fedora Linux already supports installing to a root Btrfs file-system, but EXT4 remains the default. Going back all the way to Fedora 13 has also been the ability to do Fedora system rollbacks with Yum and Btrfs -- ten releases before it's expected to become the default file-system.
In our recent Btrfs benchmarks EXT4, F2FS, and XFS have their share of performance wins from a single solid-state drive, but Btrfs continues to steam ahead on the feature front with many interesting file-system capabilities only rivaled by ZFS.
Fedora 23 is likely to be released in late 2015.