[csw-maintainers] NFS-style /opt/csw, and zfs root, beadm,

[Philip Brown]

Among the other things of interest I read from the summer camp
minutes, I read with interest, the discussion on /opt/csw, and
handling it in NFS-clean ways, etc.

An additional point in its favour that I just discovered, relates to
having a zfs root, and solaris's new, configurable "boot
environments".
(which work even in regular Solaris, since MU8 I think)

Recap for those unfamiliar with it:
Once you have a ZFS root filesystem, the "beadm" command lets you take
"root" filesystem snapshots; presumably for pre-OS-patch purposes, so
you have a quick-n-easy revert target if things go horribly wrong. For
what it's worth, its relatively easy:
the beadm command both sets up a named, snapshot, AND adds an
additional labeled entry in the boot-time grub menu for you to select
it if you wish.

So, things get interesting when you decide that you do NOT wish to
have /opt/csw as part of your "root filesystem", but have a separate
one. (reasons on WHY you might do this later)
If you have a separate filesystem, created as a zfs filesystem in your
normal "pool", then /opt/csw will get nicely and automatically
mounted,reguardless of which boot environment you start things up in.
Hurray! ?
BUT... if you are not booted from your original boot environment, or a
derivative of it...
you have now lost ALL your /etc/opt/csw files. You now see ONLY what
is under /opt/csw


Now the PS on why you may choose to do this separate /opt/csw
approach? I can think of at least 2 reasons:
1. You plan on deliberately keeping multiple "Boot Environments"
around, for testing purposes.
Sure, you might choose to use virtual environments for that sort of
thing, but this multiboot type approach is a more complete test. You
could even switch between Solaris(FCS) and OpenSolaris [and possibly
SolarisExpress(tm)(R)], I think.
2. You want to keep a backrevved version of your months-old boot
environment handy, "Just in case".... but you dont want to throw away
a couple of gigabytes in needless snapshot data of /opt/xyz as it
changes over time, just to preserve your old *OS* information