ZFS boot

[Matthew Dillon]

:To Matt:
:	since 'small' nowadays is big enough to hold /, what advantages are there
:in having root split up?
:also, having this split personality, what if the disk goes? the hammer/zfs
:is probably raided ...

    You mean /boot + root , or do you mean /root vs /usr vs /home?  I'll
    answer both.

    With regards to /boot + root.  A small separate /boot partition
    (256m) allows your root filesystem to use an arbitrarily complex
    topology.  e.g. multiple geom layers, weird zfs setups, etc.  So
    you get flexibility that you would otherwise not have if you went
    with a directly-bootable ZFS root.

    /boot can be as complex as boot2 allows.  There's nothing preventing
    it from being RAIDed if boot2 supported that, and there's nothing
    preventing it (once you had ZFS boot capabilities) from being ZFS
    using a topology supported by boot2.  Having a sparate /boot allows
    your filesystem root to use topologues boot2 would otherwise not
    support.

    With regards to the traditional BSD partitioning scheme, having a
    separate /usr, /home, /tmp, etc... there's no reason to do that stuff
    any more with ZFS (or HAMMER).  You just need one, and can break it
    down into separate management domains within the filesystem
    (e.g. HAMMER PFS's).  That's a generic statement of course, there
    will always be situations where you might want to partition things
    out separately.

    Most linux dists don't bother with multiple partitions any more.
    They just have '/' and maybe a small boot partition, and that's it.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>