But if we compare the status of ZFS with BTRFS. Here we see a RedHat developer that has been asked to evaluate BTRFS for Enterprise use.
"In the meanwhile I confirm that Btrfs design is completely broken: records stored in the B-tree differ greatly from each other (it is unacceptable!), and the balancing algorithms have been modified in insane manner. All these factors has led to loss of *all* boundaries holding internal fragmentation and to exhaustive waste of disk space (and memory!) in spite of the property "scaling in their ability to address large storage".
It seems that nobody have reviewed Btrfs before its inclusion to the mainline. I have only found a pair of recommendations with a common idea that Btrfs maintainer is "not a crazy man". Plus a number of papers which admire with the "Btrfs phenomena". Sigh.
The first obvious point here is that we *can not* put such file system to production."
Good luck to the BTRFS users!