"This next-generation Linux file-system that has often been compared to Sun's ZFS has not really performed that well, granted it's still very much under development. Btrfs is far from being the performance king and even its SSD mode has had little positive effect. Just weeks ago we delivered EXT4, Btrfs, and NILFS2 benchmarks, but now there is a new release of Btrfs available. Committed to the Linux 2.6.31 kernel was Btrfs v0.19. Does this release bring any performance improvements? Yes and no.
"The Btrfs v0.19 notes mention, "In general, v0.19 is a dramatic speed improvement over v0.18 in almost every workload." One of the key changes in this new development release is the file-system has changed the way that extent back references are recorded, and this new way should be significantly more efficient. As a sign that this new file-system is still not yet stabilized, there is a forward-rolling format change where kernels using the older version of Btrfs will be unable to read partitions created under this newer version of Btrfs."
