On Tue, 12 Mar 2002, Erik Trulsson wrote:
> There are two reasons for booting into single-user. One is to make sure
> that the machine is "quiet" since any programs running might get
> confused as the system is changed underneath them.
> The other is to allow you to check that the newly-built kernel is
> working properly before you install all the user-land programs.
> It is easy to go back to using an older kernel but reversing an
> installworld is not so easy.
>
> Now, if you can ensure that the machine is "quiet" in some other way,
> for example by not running any applications yourself and making sure
> nobody else is logged in, and are confident that the new kernel will
> work then there is no reason you can't do a remote upgrade.
>
> I have done remote upgrades on my computer several times without any
> major problems but YMMV.
There also seems to be a bit of a push to get /usr (and /) read-only. If
you can manage that, then an alternative (fast) upgrade mechanism looks
like this:
- mirror (copy) / and /usr to spare partition
- mount copy of / and /usr somewhere out of the way
- run the upgrade on the off-line copy
- reboot into the mirrored system
- if that worked ok, switch your notion of "live" and "copy".
It'd be really nice if the bootloader could fall back to the known good
state, should the reboot fail. Otherwise, you're stuck with a serial
console to try to figure things out.
Sun have something like this for Solaris; it's a neat trick.
--
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
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