Talk:FAQ

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Usability of Oracle ZFS pool versions 29 and greater

The current statement –  … not compatible – is relatively blunt and does not do justice to related projects.

Should we:

a) add a page, Usability of Oracle ZFS pool versions 29 and greater; or

b) attempt to organise the projects page to reflect peoples' interests in compatibility with Oracle ZFS?

For what it's worth, at the time of writing I favour a separate page because:

  • (unless I'm mistaken) I recall reading that an import of v29 or greater may be (-f) forced with at least one flavour of OpenZFS … and I assume that readonly=on would be sane … and use in this way would be unsupported, and so on – that's too much for an answer to an FAQ (aim to keep the FAQ page short and sweet) and debatably not a good fit with the projects page.

--Grahamperrin (talk) 06:33, 27 September 2013 (UTC)

Linux licensing questions

What is the conflict between CDDL and GPLv2 licenses?

The CDDL and GPLv2 conflict when you distribute a binary derived in part from code under the CDDL and in part from code under the GPLv2. The conflict occurs because:

  • Section 2b of the GPLv2 requires that works derived, in whole or in part, from GPLv2 code be available in whole under the GPLv2.
  • Both the CDDL (section 3.4) and the GPLv2 (section 6) disallow the imposition of additional restrictions.

Note that the notion of a derivative work is a legal concept and is therefore subject to legal nuances.

Does the conflict prevent a merge of ZFS into the Linux source tree?

No. This would be considered an aggregate redistribution of source code, which is not restricted by either license. The official GPL FAQ explicitly states that the redistribution of aggregates is okay.

Does the conflict prevent redistribution of binary ZFS kernel code for Linux?

Discussions of ports to Linux of proprietary software as loadable kernel modules established that ports of code from other operating systems to Linux are not derivative works of Linux.

It is:

  • Fine to build and redistribute binary ZFS kernel modules (i.e. CONFIG_ZFS=m)
  • Unacceptable to redistribute any Linux kernel binary that contain ZFS code (i.e. CONFIG_ZFS=y) – the Linux kernel binary is a derivative work of Linux and must be distributed in whole under the terms of the GPLv2 as per section section 2b of the GPL.

The ZFS on Linux project also maintains its own FAQ entry on this.

How do the four [zfs-discuss] lists relate to each other?

When searching the Internet for general information about ZFS, it may be not immediately clear that some zfs-discuss content is very platform-specific.

[zfs-discuss] (2005–2013)

… at opensolaris.org began for the OpenSolaris ZFS community. Partial archives:

[zfs-discuss] (2006–2009)

… at lists.macosforge.org began for the Mac community. A partial archive:

[zfs-discuss] (2010–)

… at Google Groups began for the ZFS on Linux community. Alternative interfaces:

[zfs-discuss] (2013–)

… at solaris-zfs.java.net began for the Oracle Solaris community and was described as a move from the original [zfs-discuss]. Alternative interface:

More alternative views of ZFS-related groups/lists

The MarsHut ZFS Timeline seems to present a mixture of at least:

  • both of the current [zfs-discuss] lists/groups
  • the MacZFS-devel group

– but not the zfs-macos group.

Quotes in Google Groups are misrepresented in MarsHut; if in doubt, seek the original post.


Are dates correct? (Year only should suffice.)

This question about the four lists may be not frequently asked by developers, but the lack of an overview can be a source of frustration when seeking platform-agnostic information. (OpenZFS will do much for coherence but – in Google search results and so on – the potentially confusing effects of the multiplicity may be long-lasting.) 

I'm floating this on the Talk:FAQ page before a possible move to the main FAQ … or will some other main page be suitable?

--Grahamperrin (talk) 01:11, 28 September 2013 (UTC)

--Grahamperrin (talk) 06:49, 6 October 2013 (UTC)