Host ID.
Robert Watson
rwatson at FreeBSD.org
Sun Apr 8 10:19:02 UTC 2007
On Sun, 8 Apr 2007, Dag-Erling Smørgrav wrote:
> Pawel Jakub Dawidek <pjd at FreeBSD.org> writes:
>> If we move disks with root file system, it's this more or less the same
>> host, isn't it?
>
> No. I recently installed three servers by replicating the disk from a
> fourth and changing the host name and IP address in rc.conf.
Yes, one of the nice properties of FreeBSD -- as opposed to, say, Windows, is
that it's trivial to install a hundred boxes by dropping the same image onto
all of them and configuring host-specific parameters using DHCP. But there is
a tricky tension here: the notion of a persisting host ID is very useful, in
the a similar way to the way in which a persisting SSH host key is useful.
If we're going to adopt a host ID model, we may want to make generation and
configuration of the host ID conditional on an explicit variable in rc.conf
(i.e., hostid_enable="YES" which causes it to be generated the first time and
loaded future times, similar to SSH keys), and make it very easy to force a
regen. That way, you can image the boxes with the rc.conf setting set, but
they don't generate host IDs until they boot the first time.
Robert N M Watson
Computer Laboratory
University of Cambridge
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