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

Grub

[jshriverWVU]

Booting from a ZFS partition has been confirmed to work

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

Cheesy Intro to ZFS Video

[kaleco]

If you can suffer the bizarre presentation style Sun have used for this video, it's quite informative about the benefits of ZFS.

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.

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.

"The FSF guideline is"

[Per Abrahamsen]

The FSF has used the syscall interface as a guideline to determine whether something is a derived work or not. It is a guideline, not a hard rule though, and I suspect they would consider user-space ZFS for a derived work using a technical trick to avoid being linked into the kernel. I.e. infringing. However, since the FSF doesn't own the kernel, their opinion on the subject doesn't matter.

Re:Why not in the kernel?

[BrainInAJar]

or they could avoid the hassle of managing a dual licensed project & the inevitable GPL-only fork ( what happens if someone wants to import a driver from linux? that's an instant fork ) by keeping the perfectly-fine license they have right now

relicensing Solaris as GPL is entirely unnecessary and doesn't help Sun or Solaris at all... the only people it helps is Linux, and that shouldn't be the primary concern of OpenSolaris.

If OpenSolaris happens to help Linux, great, but it shouldn't hurt itself & go out of it's way to do it

Re:Why not in the kernel?

[the_womble]

Linux does NOT use the "standard GLP" it makes a few changes for example he removed the "and later versions" part.

Wrong. Here is the COPYING file for the Linux kernel.

He has added a note clarifying that userland programs making system calls are not derivative works. That is clarifying his interpretation of the license. At the most, it adds an exemption, which is common practice.

The "and later versions" clause is not part of the GPL, it lies outside it. In effect, it makes the work automatically multiple licensed as and when new versions of the GPL comes out: so if you distribute something under GPL v2 with that clause, when v3 comes you it will become dual licensed under 2 and 3, when v 4 comes out it will be triple licensed etc. This allows people to redistribute under v2 or any later version, with or without the "and later versions" clause.

Re:Why not in the kernel?

[mabinogi]

There is no license that gives you the right to re-license someone else's copyrighted work.
The GPL doesn't require that everything linked to it be GPL'd, it requires that any changes or derivative works be licensed under a license (any license) that adds no more restrictions than the GPL itself does.