Linus Torvalds Doesn't Recommend Using ZFS On Linux
Linux kernel creator Linus Torvalds doesn't recommend using ZFS On Linux at least until Oracle were to re-license the code to make it friendly for mainline inclusion. But even then he doesn't seem turned on by the ZFS features or general performance.
Derailed from the recent mailing list discussion over Torvalds' thoughts on the Linux kernel scheduler, he responded to a post of a user complaining about the Linux kernel recently breaking the out-of-tree ZFS module.
Of course, Linus Torvalds has little control over the behavior of out-of-tree modules and it's always been his position to not maintain a stable driver API/ABI and they won't bend over backwards for closed-source/out-of-tree code. Out-of-tree modules are basically treated like they don't exist.
Linus wrote of ZFS on Linux:
Note that "we don't break users" is literally about user-space applications, and about the kernel I maintain.
If somebody adds a kernel module like ZFS, they are on their own. I can't maintain it, and I can not be bound by other peoples kernel changes.
And honestly, there is no way I can merge any of the ZFS efforts until I get an official letter from Oracle that is signed by their main legal counsel or preferably by Larry Ellison himself that says that yes, it's ok to do so and treat the end result as GPL'd.
Other people think it can be ok to merge ZFS code into the kernel and that the module interface makes it ok, and that's their decision. But considering Oracle's litigious nature, and the questions over licensing, there's no way I can feel safe in ever doing so.
And I'm not at all interested in some "ZFS shim layer" thing either that some people seem to think would isolate the two projects. That adds no value to our side, and given Oracle's interface copyright suits (see Java), I don't think it's any real licensing win either.
Don't use ZFS. It's that simple. It was always more of a buzzword than anything else, I feel, and the licensing issues just make it a non-starter for me.
The benchmarks I've seen do not make ZFS look all that great. And as far as I can tell, it has no real maintenance behind it either any more, so from a long-term stability standpoint, why would you ever want to use it in the first place?