ZFS On Linux - It's Alive!

lymeca writes "LinuxWorld reports that Sun Microsystem's ZFS filesystem has been converted from its incarnation in OpenSolaris to a module capable of running in the Linux user-space filsystem project, FUSE. Because of the license incompatibilities with the Linux kernel, it has not yet been integrated for distribution within the kernel itself. This project, called ZFS on FUSE, aims to enable GNU/Linux users to use ZFS as a process in userspace, bypassing the legal barrier inherent in having the filesystem coded into the Linux kernel itself. Booting from a ZFS partition has been confirmed to work. The performance currently clocks in at about half as fast as XFS, but with all the success the NTFS-3g project has had creating a high performance FUSE implementation of the NTFS filesystem, there's hope that performance tweaking could yield a practical elimination of barriers for GNU/Linux users to make use of all that ZFS has to offer."

Comments

Why not in the kernel?

[seanadams.com]

The in-kernel vs userland distinction has always struck me as quite arbitrary. So in one case you're linked at compile time and in another case you compile them separately and go through system calls. Why should that make one of them a derivative work and the other not? In either case the file system can be taken out and you still have a perfectly functional kernel that can run other file systems. Same goes for graphics drivers.

The GPL doesn't attempt to codify all the intricate details that it would take to define such a distinction in the license. It's only described as an accepted rule of thumb in the FAQ. So what's the deal? It seems like this rule is really holding back some commercial support for Linux - is the current situation what we really want, and at any rate how did we get here? Would we be better off if such a separable, non-essential feature could be linked in somehow instead of needing to be put behind extra layers of abstraction?

Re:Why not in the kernel?

[notamisfit]

The version of the GPL included with the Linux kernel states at the top:

• NOTE! This copyright does *not* cover user programs that use kernel services by normal system calls - this is merely considered normal use of the kernel, and does *not* fall under the heading of "derived work".

Not sure how far back this clarification really goes, but I think it predates the GPLv2-only one, making it at least six years old.

Grub

[jshriverWVU]

Booting from a ZFS partition has been confirmed to work

Grub has supported ZFS booting for a while (forget which branch though).

Parts of ZFS already GPLv2'd

[andrewd18]

According to Darren Moffat at SUN, parts of ZFS are already licensed under the GPL v2. Maybe there is still hope for a native solution. Not, of course, that I mind using FUSE.

http://blogs.sun.com/darren/entry/zfs_under_gplv2_ already_exists

Now about that headline, yes I really did say that ZFS code is already available under the GPLv2. I will be completely honest though and make it clear that it isn't all of the ZFS source. It is, sufficient amount to be able to boot an OpenSolaris based system from GRUB, that means that support for mirroring and the checksum and compression support is there but radiz isn't nor are the userland commands. It is possible that this might be enough to get someone started. Still don't believe me check out the updated GRUB source on opensolaris.org, specifically all the files with zfs in their name - every single one of them under the GPLv2 or later.