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Comment by chmike | Hacker News Reader

How production ready is ZFS on Ubuntu (Debian?) ? Is there any risk of Oracle fighting back open source zfs as for Java with Google and Android ?

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ZFS is actually one of those features that are officially supported on Ubuntu but not on Debian. As far as I know, Ubuntu 16.04 is the first popular Linux OS to support ZFS out of the box.[1]

As the article notes, ZFS on Linux has been production-ready and stable for over three years. For in-depth info see [2].

[1] https://wiki.ubuntu.com/ZFS

[2] https://clusterhq.com/2014/09/11/state-zfs-on-linux/

If you have been following the case, Google switched from Apache Harmony to OpenJDK saying that Oracle had no basis for claims against future versions because the code is now under license from Oracle. The original ZFS code has always been under the CDDL from Sun and later Oracle. The ZoL code is derived from that, so it should be in the same situation where Oracle cannot make claims against their own licensee.

ZFS is under the CDDL while Java is not under the CDDL.

CDDL is an open-source licence just as the GPL.

> CDDL is an open-source licence just as the GPL

But incompatible with the GPL, which mostly explains the current situation of ZFS on Linux.

It's the GPL that's incompatible with the CDDL and not the other way around, which is an important distinction. Other than other GPL variants and BSD and MIT style licenses, the GPL has restrictions which make it pretty much incompatible with everything.

I don't get how the word "incompatible" can be understood as anything other than both license has aspects which makes combining them impossible. But owell, lets see what the license text actually say:

Any Covered Software that You distribute or otherwise make available in Executable form must also be made available in Source Code form and that Source Code form must be distributed only under the terms of this License. The Modifications that You create or to which You contribute are governed by the terms of this License.

If you distribute source code, this license means that you must use this license. You can't use some other license, as its not compatible with the distributor deciding what license to use. CDDL license require that any source code distribution use CDDL as its license, and it is incompatible with any other license that has similar condition. CDDL is incompatible with GPL because GPL has similar conditions as CDDL.

If we were to make an identical copy of the CDDL license and call it CDDLv2, those two identical twins would be incompatible with each other. Software under CDDLv1 would not be permitted to be combined with software under CDDLv2 and distributed as source code.

Actually, the CDDL allows the person who wrote the License (Sun, now Oracle) to release a new version of the license that implicitly updates the license for all projects using the old license (It's like the "or any later version" thing with the GPL, but I'm fairly sure it's not optional with CDDL). Which is why people are asking why Oracle doesn't just release CDDL 2.0 that is GPL compatible.

New CDDL code outside of Oracle is under CDDLv1 only to prevent them from doing as they please with the license terms.

But ZFS is not under that other license (which might be called CDDLv1, but that's confusing). I don't get why new software uses the CDDL over the MPL if you want "file based copyleft". If you want copyleft, just use the GPL.

Not much new software uses the CDDL. Fans of CDDL software typically opt for BSD or Apache licenses.

> If we were to make an identical copy of the CDDL license and call it CDDLv2, those two identical twins would be incompatible with each other. Software under CDDLv1 would not be permitted to be combined with software under CDDLv2 and distributed as source code.

There is a CDDL v1.1 that is effectively 's/Sun/Oracle/'. The CDDL has an optional clause saying any later version is allowed and the CDDL only applies at the file level. I have yet to see a problem in mixing CDDL code under v1 and v1.1 with each other.

Okey, correction then, if you are not Sun/Oracle (and most people aren't) and create an identical copy of CDDL and call it "bobs license", then BL and CDDL is incompatible because of the conditions in the otherwise identical licenses. Point being, the condition that create the incompatibility between CDDL and GPL is that both want their license to be used when distributing. Remove that condition from either license, that is CDDL or GPL, and the license incompatibility goes away. It would also turn either license into a permissive license.

The CDDL's restriction is only in the files containing the code. The GPL's restriction is on all files within a derived work, whether they contain GPL code or not.

Is you argument that CDDL condition is somehow smaller in scope than GPL? GPLv3 also cover anti-DRM clauses, but that doesn't make it more or less compatible with CDDL requirement that source code is made available only under CDDL license.

If CDDL did not have their condition that source code is only made available under CDDL license, then the incompatibility would not exist. If GPL had similar loophole as CDDL and permitted modifications to be under different license if they are put as a separate file node in the file system, then the two permissions would permit a single project to include software under both licenses. I doubt CDDL will receive such update, and there is already LGPL.

The loophole is quite interesting from a legal point of view. Would a filesystem based on a database be fine? The computer would be storing all the code in a single file, but the presentation would look like that file is actually two different ones. Same goes with a gz file and "virtual" file systems, that present data inside as if it were separated files on the disk. What about a container image where a single work has source code under CDDL and source code under some other license?

The CDDL is designed to be a per-file license. All other files in a project can be proprietary as far as it is concerned as long as the files containing CDDL code are under the CDDL. Sun wanted it that way. The GPL's insistence that CDDL covered files be under it when they are used as part of a derived work (in the legal sense) is why incompatibility can occur.

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