Lucid Nonsense


ZFS, again

Wednesday, 17 June 2009

Well sadly it does look like ZFS is no longer due to be a headline feature in Snow Leopard. As mentioned in my last entry it has disappeared from the tech specs page for 10.6 Server.

This is disappointing for a number of reasons, mainly because if Apple included ZFS with OS X Server there would be a certain level of guarantee that it would play well with all of the system features. The current build of ZFS for Leopard, build 119 available from MacOSforge, does not play well with all Mac OS X components. This includes fairly pervasive features such as Spotlight, the lack of which would dent the appeal of ZFS as backing storage for an AFP server, as Spotlight over AFP tends to be very popular with users. There are also certain stability issues with that build, so anyone using it to try and gauge the state of ZFS on Mac OS X may be a little disappointed.

There are reasons for a little optimism however. Firstly, build 119 is old. Really old. It hasn’t been updated for nearly a year, and as ZFS has only recently been removed from Snow Leopard server as a major feature, it’s fairly safe to assume that Apple have builds of ZFS running internally that have had significantly more development time spent on them than build 119. Secondly, some of the current problems with build 119 are related to the fact that it is built on older versions of the main ZFS code (Solaris build 72). Several useful features have been added with later versions of the main ZFS trunk, including being able to set whether ZFS forces a kernel panic when it loses connection to a drive (most Mac OS X admins would find such behaviour a little extreme to say the least). That feature in particular was added in Solaris build 77.

It’s also worth bearing in mind that ZFS is a sufficiently different filesystem to those that most Mac users are used to that there is certainly the potential that a reason for dropping ZFS as an included feature of Snow Leopard Server has at least something to do with difficulties in making the filesystem easy to configure, and easy to manage, via the Disk Utility GUI. I’m sure Apple would also like a competent interface for browsing ZFS snapshots as well.

ZFS is a production filesystem on Solaris systems, and Apple have had a year to work on their port since the last public release. I would be willing to bet that when Snow Leopard Server is released it is closely followed by a ZFS build that is absolutely suitable for system administrators to use, even if it is lacking some of the GUI polish and ease-of-use features that Apple are well known for. Still, for sys admins I’m starting to lean back towards ZFS being a viable option for Snow Leopard Server systems upon its release this September.

We will have to wait and see.


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