“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.”
This is what Linus Torvalds said in a mailing list to once again express his disliking for ZFS filesystem specially over its licensing.
To avoid unnecessary confusion, this is more intended for Linux distributions, kernel developers and maintainers rather than individual Linux users.
What’s the licensing issue with ZFS and the Linux kernel?
ZFS was open sourced around 2003. This would have meant that Linux distributions start supporting ZFS. But that didn’t really happen because of the complexity of open source licenses.
ZFS is open source under Common Development and Distribution License (CDDL) 1.0 whereas Linux kernel is licensed under the GNU General Public License (GPL) 2.0.
These two open source licenses are not fully compatible with each other. As noted by PCWorld, if ZFS with this license is included in the Linux kernel, this would mean that kernel+ZFS is a derivative work of the (original ZFS-less) Linux kernel.
Torvalds doesn’t trust Oracle
While the whole derivative thing is a matter of debate for legal and licensing experts, Torvalds is skeptical of Oracle. Oracle has a history of suing enterprises for using its code. Remember Oracle vs Android lawsuit over the use of Java?
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.
Torvalds doesn’t want Linux kernel to get into legal troubles with Oracle in future and hence he refuses to include ZFS in the mainline kernel until Oracle provides a signed letter that a kernel with ZFS will be under GPL license.
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.
He is not stopping other (distributions) from using ZFS. But they are on their own.
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.
Canonical, Ubuntu’s parent company, has been too keen on ZFS. Their legal department thinks that including ZFS in the kernel doesn’t make it a derivative work. So they took their chances and now they provide an option to use ZFS on root from Ubuntu 19.10.
Torvalds is also not impressed with ZFS in general
While some people drool over ZFS, Linus Torvalds is not that impressed with ZFS. He doesn’t think it’s using ZFS is a good idea specially when it is not actively maintained by Oracle (after they open sourced it)
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?
I am no legal expert but if there is even a slightest doubt, I would prefer staying away from ZFS. What do you think of the whole ZFS debate?
I personally think that ZFS is a great file system. Yes, I agree the performance of adding new files is not great, but as it gives me reliability, snapshots, COW, resync of outdated drives then this is a best filesystem I have used and I will use it in the future.
For all people who have performance issues – Don’t use raids use mirrors. They are also not great in performance but ok.
I have a pool which is a mirror of 4 HDDs. 2 HDDs constantly connected to it. Once in 3 months I connect one of the other 2 drives to resync and data check, after synch I move that drive to backyard.
So with that filesystem I have protection: from my mistakes, fire and theft. Most important thing is snapshots!!! I wish I new about that filesystem much earlier. If I would be given a chance to go back and tell to myself to use that file system I would happy to pay $3000.
I got sick buying new drives and numerous copies of my personal data which is slightly different. I could not manage all of it. I gradually getting to a state that I can manage all my data.
Maybe, just maybe, if Linus and the kernel developers were a little more optimistic and actually tried working with Oracle to GPL zfs rather than quickly dismissing it as a buzz word.. Things would be different. Zfs is greatly needed in Linux by anyone having to deal with very large amounts of data. This need is growing larger and larger every year that passes.
alternatives ?