7 ms·

There's literally ZFS-on-linux and it works great. And yes, I will once again say Linus is completely wrong about ZFS and the multiple times he's spoken about i

• evanjrowley 1y ago
  Sometimes I wonder how someone so talented could be so wrong about ZFS, and it makes me wonder if his negative responses to ZFS discussions could be a way of creating plausible deniability in case Oracle's lawyers ever learn how to spell ZFS.
  • wmf 1y ago
    If Linus has never touched ZFS that's not plausible deniability. That's actual deniability.
    • MathMonkeyMan 1y ago
      The most plausible deniability!
  • chao- 1y ago
    How many years has it been since Ubuntu started shipping ZFS, purportedly in violation of whatever legal fears the kernel team has? Four years? Five years? I obviously have nothing like inside knowledge, but I assume the reason there have not been lawsuits over this, is that whoever could bring one (would it be only Oracle?) expects there are even-odds that they would lose? Thus the risk of setting an adverse precedent isn't worth the damages they might be awarded from suing Canonical?
    • tuna74 1y ago
      It could be a long term strategy by Oracle to be able to sue IBM and other big companies distributing Linux with ZFS built in. If Oracle want people to use ZFS they can just relicense the code they have copyright on.
      • p_l 1y ago
        Oracle does not have copyright on OpenZFS code - only on the version in Solaris. The code in OpenZFS and Solaris has diverged after Oracle closed OpenSolaris.
        • messe 1y ago
          > The code in OpenZFS and Solaris has diverged after Oracle closed OpenSolaris. Diverged. Not rewritten entirely.
          • m-p-3 1y ago
            Sure, but Oracle cannot retroactively relicense the code already published before then. The cat's already out of the bag, and as long as the code from before the fork is used according to the original license, it's legal.
            • messe 1y ago
              I think you might have missed the point. Yes. Oracle have that copyright. That's the whole fucking point. Anything from before the fork is still licensed (and pretty much everything after) is still under the CDDL which is possibly in conflict with the GPL.
              • p_l 1y ago
                Oracle can't do anything. They can't relicense code that was already released as CDDL in any form other than what they did when they closed down Solaris. The CDDL being unacceptable is the same issue that GPL3 or Apache is unacceptable - unlike GPLv2, CDDL mandates patent licensing as far as the code is considered.
                • cyphar 1y ago
                  Oracle is the license steward for CDDL, they have the right to release CDDL-2.0 and make it GPL-compatible which users would then be allowed to chose to use. Mozilla did the same thing with MPL-2.0 (CDDL was based on MPL-1.0), though the details are a little more complicated. Unlike the GPL, the CDDL (and MPL) has an opt-out upgrade clause and all of OpenSolaris (or more accurately, almosf all software under the CDDL) can be upgraded to "CDDL-1.1 OR CDDL-2.0" unilaterally by Oracle even if they do not own the copyrights. See section 4 of the CDDL.
    • p_l 1y ago
      The legal issues between Linux kernel and ZFS are that Linux license does not allow incorporating licenses with more restrictions - including anything that puts protections against being sued for patented code contributed by license giver.
      • chao- 1y ago
        I am aware of that. I did a bad job phrasing my post, and it came off sounding more confident than I actually intended. I have two questions: (1) What are the expected consequences of a violation? (2) Why haven't any consequences occurred yet? My understanding is that Canonical is shipping ZFS with Ubuntu. Or do I misunderstand? Has Canonical not actually done the big, bad thing of distributing the Linux kernel with ZFS? Did they find some clever just-so workaround so as to technically not be violation of the Linux kernel's license terms? Otherwise, if Canonical has actually done the big, bad thing, who has standing to bring suit? Would the Linux Foundation sue Canonical, or would Oracle? I ask this in all humility, and I suspect there is a chance that my questions are nonsense and I don't know enough to know why.
        • p_l 1y ago
          Oracle has no standing. Additionally, GPLv2 does not prevent shipping ZFS combined with GPL code, because CDDL code is not derivative work of GPLv2 code. So it's legal to ship. It could be problematic to upstream, because kernel development would demand streamlining to the point that the code would be derivative. Additionally, two or three kernel contributors decided that the long standing consensus on derivative work is not correct and sued Canonical. So far nothing happened out of that, Los Alamos National Laboratory also laughed it off.
          • tzs 1y ago
            > Additionally, GPLv2 does not prevent shipping ZFS combined with GPL code, because CDDL code is not derivative work of GPLv2 code. So it's legal to ship. The CDDL code is not a derivative work of GPLv2 code, but the combined work as a whole is a derivative work of GPLv2 code (assuming by "combined" we are talking about shipping an executable made by compiling and linking GPLv2 and CDDL code together). Shipping that work does require permission from both the GPLv2 code copyright owners and the CDDL code copyright owners unless the code from on or the other can be justified under fair use or if it was a part of the GPLv2 or CDDL code that is not subject to copyright. What Canonical does is ship ZFS as a kernel module. That contains minimal GPLv2 code from the kernel that should be justifiable as fair use (which seems like a decent bet after the Oracle vs Google case).
  • p_l 1y ago
    Oracle lawyers know how to spell ZFS. But Sun ensured that they can only gnash their teeth. The source of "license incompatibility" btw is the same as from using GPLv3 code in kernel - CDDL adds an extra restriction in form of patent protections (just like Apache 2)
  • aaronmdjones 1y ago
    As far as I know, the license incompatibility is on the GPL side of the equation. As in, shipping a kernel with the ZoL functionality is a violation of the GPL, not the CDDL. Thus, Oracle would not be able to sue Canonical (Edit: or, rather, have any reasonable expectation of winning this battle), as they have no standing. A copyright holder of some materially significant portion of the GPL code of the kernel would have to sue Canonical for breaching the GPL by including CDDL code. I am not a lawyer.
    • ajb 1y ago
      Oracle do also make GPL'd contributions to the Linux kernel. So by that reasoning , they would have standing. It would be an interesting lawsuit as the judge might well ask why as copyright holder of ZFS they can't solve the problem they are suing over. But I think you underestimate the deviousness of oracle's legal dept.
      • koverstreet 1y ago
        If it ended up before Alsup we'd be fine. Venue shopping being what it is, though...
    • cyphar 1y ago
      The Software Freedom Conservancy did a legal analysis and concluded that the incompatibility comes from both sides[1]. This also applies to the pre-2.0 MPL that CDDL was based on. A lot of people focus on the fact that the CDDL allows binaries to be arbitrarily licensed so long as you provide the sources, but the issue is that the GPL requires that the source code of both combined and derived works be under the GPL and the CDDL requires that the source code be under the CDDL (i.e., the source code cannot be sublicensed). This means that (if you concluded that OpenZFS is a derived work of Linux or that it is a combined work when shipped as a kernel module) a combination may be a violation of both licenses. However, the real question is whether a judge would look at two open source licenses that are incompatible due to a technicality and would conclude that Oracle is suffering actual harm (even though OpenZFS has decades of modifications from the Oracle version). They might also consider that Oracle themselves released DTrace (also under the CDDL) for their Linux distribution in 2012 as proof that Oracle doesn't consider it to be license violation either. If we did see Canonical get sued, maybe we'd finally be able to find out through discovery if the CDDL was intentionally designed to be GPL incompatible or not (a very contentious topic). [1]: https://sfconservancy.org/blog/2016/feb/25/zfs-and-linux/ https://sfconservancy.org/blog/2016/feb/25/zfs-and-linux/
• koverstreet 1y ago
  ZFS deserves an absolutely legendary amount of respect for showing us all what a modern filesystem should be - the papers they wrote, alone, did the entire filesystem world such a massive service by demonstrating the possibilities of full data integrity and why we want it, and then they showed it could be done. But there's a ton of room for improvement beyond what ZFS did. ZFS was a very conservative design in a lot of ways (rightly so! so many ambitious projects die because of second system syndrome); notably, it's block based and doesn't do extents - extents and snapshots are a painfully difficult combination. Took me years to figure that one out. My hope for bcachefs has always been to be a real successor to ZFS, with better and more flexible management, better performance, and even better robustness and reliability. Long road, but the work continues.
  • TheAceOfHearts 1y ago
    > But there's a ton of room for improvement beyond what ZFS did. Say more? I can't say I've really thought that much about filesystems and I'm curious in what direction you think they could be taken if time and budget weren't an issue.
    • koverstreet 1y ago
      that would be bcachefs :) It's an entirely clean slate design, and I spent years taking my time on the core planning out the design; it's as close to perfect as I can make it. The only things I can think of that I would change or add given unlimited time and budget: - It should be written in Rust, and even better a Rust + dependent types (which I suspect could be done with proc macros) for formal verification. And cap'n proto for on disk data structures (which still needs Rust improvements to be as ergonomic as it should be) would also be a really nice improvement. - More hardening; the only other thing we're lacking is comprehensive fault injection testing of on disk errors. It's sufficiently battle hardened that it's not a major gap, but it really should happen at some point. - There's more work to be done in bitrot prevention: data checksums really need to be plumbed all the way into the pagecache I'm sure we'll keep discovering new small ways to harden, but nothing huge at this point. Some highlights: - It has more defense in depth than any filesystem I know of. It's as close to impossible to have unrecoverable data loss as I think can really be done in a practical production filesystem - short of going full immutable/append only. - Closest realization of "filesystem as a database" that I know of - IO path options (replication level, compression, etc.) can be set on a per file or directory basis: I'm midway through a project extending this to do some really cool stuff, basically data management is purely declarative. - Erasure coding is much more performant than ZFS's - Data layout is fully dynamic, meaning you can add/remove devices at will, it just does the right thing - meaning smoother device management than ZFS - The way the repair code works, and tracking of errors we've seen - fantastic for debugability - Debugability and introspection are second to none: long bug hunts really aren't a thing in bcachefs development because you can just see anything the system is doing There's still lots of work to do before we're fully at parity with ZFS. Over the next year or two I should be finishing erasure coding, online fsck, failure domains, lots more management stuff... there will always be more cool projects just over the horizon
• quotemstr 1y ago
  > works great. I will not use or recommend ZFS on _any_ OS until they solve the double page cache problem. A filesystem has no business running its own damned page cache that duplicates the OS one. I don't give a damn if ZFS has a fancy eviction algorithm. ARC's patent is expired. Go port it to mainline Linux if it's not that good. Just don't make inner platform.
  • IgorPartola 1y ago
    That’s such a weird hill to die on. It’s like refusing to drive a car because it uses head bolts instead of head studs in an engine.
• mort96 1y ago
  To me, ZFS on Linux is extremely uninteresting except for the specific use case of a NAS with a bunch of drives. I don't want to deal with out-of-tree filesystems unless I absolutely have to. And even on a NAS, I would want the root partition to be ext4 or btrfs or something else that's in the kernel.
  • rob_c 1y ago
    > the specific use case of a NAS with a bunch of drives Aka a way bigger part of the industry than it should probably still be ;)
• m-p-3 1y ago
  I've recently started using OpenZFS after all these years, and after weighting all the pros and cons of BTRFS, mdadm, etc, ZFS is clearly on top for availability and resiliency. Hopefull we can get to a point where Linux has a native, and first-class modern alternative to ZFS with BcacheFS.