This is something that has bothered me about open source in general for a while now, why is that there is so much fragmentation? So many wheels that are being re-implemented for the sake of being re-implemented? I agree that a new file system that supports all the new features of btrFS and ZFS are required, at the same time I don't understand all of this duplication. ZFS has some features that btrFS does not have, and vice-versa, why not spend the time developing a hybrid of the two, thereby massively increasing the usability and stability of both products, or rather, of just one product since the time and effort would only be but into the hybrid.
If it is possible for Nvidia to use binary blobs for their graphics cards, it should be possible to use CDDL code with a compatibility shim in the Linux kernel. All this duplicated effort could instead be focused on one project, thereby having an all around better file system. btrFS has just recently started coming into fruition, would that time not be better spent improving ZFS?
It seems that license issues are the only thing that is causing all of this trouble in the first place. As a user of a system I don't want to spend valuable time testing all the various file systems, I also don't want to have to support all of the different file systems that are available. With a project as large as Linux, and the amount of file systems that are available, how can it be guaranteed that the file system I ultimately go with has been properly bug tested, has had the proper code review done, and is not going to be shoved aside for the next new shiny file system that is introduced? As an end-user (and I hereby don't mean the home user group) I want stability. FreeBSD gives me UFS2, I know I can depend on it, I know it will still exist tomorrow, and I know that it is still being looked at for performance improvements and improvements in general, ZFS has recently been imported and is will exist for a long time. OpenSolaris gives me UFS, and ZFS, I know it is going to be around, I know it is going to be improved. Linux gives me XFS, JFS, ext2, ext3, ext4, ReiserFS, Reiser4, and now btrFS. Depending on my workload and who I ask I get told to use different file systems on Linux. Individually testing each and everyone would be time consuming and error prone, instead of all of these different file systems make one unified file system.
For that reason, and that reason alone I use FreeBSD 7.0 and Solaris 10 on my servers. Stability is a good thing, I need some way to relay to my clients that there is a reasonable time schedule for new releases, that what they are storing their data on right now is going to be around tomorrow, and that it is stable, that it has been time proven and tested. Linux can not provide that at the moment.