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The single, actual reason for refusing to not use ZFS on Linux systems in general is IMO the non-mainline state. Sure, as with other FS it has trade-offs and m

The single, actual reason for refusing to not use ZFS on Linux systems in general is IMO the non-mainline state. Sure, as with other FS it has trade-offs and may not match all workloads or use cases, but it also has a maturity and no native Linux file systems has such a thought out and complete feature set ZFS has, albeit btrfs comes closer every release which is nice to see. The one thing ZFS is missing is rebalancing, but there are ideas out to solve that, but those are not reasons for just not singling out ZFS and never considering usage in general. Alternatively fighting with proprietary HW raid controller is risking to get one's data eaten on a simple firmware upgrade, and having no resource to introspect or salvage, because they're just a proprietary mess. So, while installing ZFS via DKMS or the like works out, in the end they'll always be a second class citizen in the kernel and spent a lot of time on fighting changes upstream, working in a parallel universe in the kernel and thus spending much more resources and effort. See for example the ARC, that is allowed to use up to half of memory by default, but it just nowhere shows up in the native Linux memory accounting, yes, some specialized tools like arcstat exist, but if ZFS was actually mainlined it could benefit from actually working with the kernel, not against it half of the time. I think that if ZFS would be mainlined, and sadly that seems very unlikely to happen anytime soon, a big part of the things causing users currently trouble when using ZFS on Linux would go away pretty soon just due to being natively integrated.

p_l 5y ago
The issue with ARC is that you can't really make it cooperate with normal linux VFS, because of how linux works. You can either break with Linux VFS (as ZFSonLinux does) or do a complete rewrite of core foundational element of Linux kernel. (No, you can't reimplement ZFS to be compatible with certain VFS expectations). There are reasons why both kernel and ZoL teams say they are happy with not mainlining.
- tlamponi 5y ago
  > The issue with ARC is that you can't really make it cooperate with normal linux VFS, because of how linux works. That's only parts of the reason, and in the simplest form you can just disable the VFS page cache and render fitting arcstat properties through it. And besides that, I see no inherent issue in solving that, at least in a much more integrated way as the status quo is now.. > There are reasons why both kernel and ZoL teams say they are happy with not mainlining. Yes, but that's the license and not the caching/VFS differences. As Linus said: > 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. > > [...] the licensing issues just make it a non-starter for me." https://www.realworldtech.com/forum/?threadid=189711&curpostid=189841 https://www.realworldtech.com/forum/?threadid=189711&curpost... And OpenZFS also wants to do so, but legal blockers and Linux maintainers not wanting to do a dual-licensed CDDL/GPL either, is their blocker: https://github.com/openzfs/zfs/issues/8314 https://github.com/openzfs/zfs/issues/8314
  - p_l 5y ago
    Oh, I haven't seen that issue. (Notice "made me reconsider" from ryao). But pagecache is still something that isn't fixable (you can't disable VFS pagecache, it's too intertwined with the whole I/O system) - I don't see a way to implement ZFS "linux way" considering things like block sizes bigger than one page being antithetical in linux.

p_l 5y ago

The issue with ARC is that you can't really make it cooperate with normal linux VFS, because of how linux works. You can either break with Linux VFS (as ZFSonLinux does) or do a complete rewrite of core foundational element of Linux kernel. (No, you can't reimplement ZFS to be compatible with certain VFS expectations). There are reasons why both kernel and ZoL teams say they are happy with not mainlining.

tlamponi 5y ago
> The issue with ARC is that you can't really make it cooperate with normal linux VFS, because of how linux works. That's only parts of the reason, and in the simplest form you can just disable the VFS page cache and render fitting arcstat properties through it. And besides that, I see no inherent issue in solving that, at least in a much more integrated way as the status quo is now.. > There are reasons why both kernel and ZoL teams say they are happy with not mainlining. Yes, but that's the license and not the caching/VFS differences. As Linus said: > 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. > > [...] the licensing issues just make it a non-starter for me." https://www.realworldtech.com/forum/?threadid=189711&curpostid=189841 https://www.realworldtech.com/forum/?threadid=189711&curpost... And OpenZFS also wants to do so, but legal blockers and Linux maintainers not wanting to do a dual-licensed CDDL/GPL either, is their blocker: https://github.com/openzfs/zfs/issues/8314 https://github.com/openzfs/zfs/issues/8314
- p_l 5y ago
  Oh, I haven't seen that issue. (Notice "made me reconsider" from ryao). But pagecache is still something that isn't fixable (you can't disable VFS pagecache, it's too intertwined with the whole I/O system) - I don't see a way to implement ZFS "linux way" considering things like block sizes bigger than one page being antithetical in linux.