What is the major problem to use zfs as the root filesystem?

[Deng Yao]

I have seen a similar question on this list, but I can't find it now,
sorry for this.
It is the bootloader, the mach_kernel or the zfs-macos package? If it
is the bootloader, maybe we can try grub2. I really like this snapshot
feature provided by zfs.

Thanks

--Yao

[Alex Blewitt]

I suspect a lot will have to happen before ZFS Boot on OSX works. For
a start, the bootloader in OSX knows how to read HFS partitions but
doesn't know about anything else - so bootstrapping the kernel can't
happen. However, OSX RAID works by having a small invisible boot
partition (formatted HFS) and uses that as a bounce to load other
kernel extensions including other file systems, so that it can then
mount the remainder of the drives.

There's a lot more to HFS than just the file system though (e.g.
Spotlight support, resource forks) and I'm not sure whether OSX itself
would be capable of running if hosted on a ZFS partition (e.g. what
about swap?)

In summary, I don't see OSX booting from ZFS any time soon because
there are number of tasks which need to be done first, as well as a
number of other nice-to-haves like NFS sharing that are probably
higher priority.

Alex