[OpenAFS] Re: IP address changes

[Peter Grandi]

[ ... ]

> 'vos changeaddr' deals with fileserver addresses, not database
> servers.  Since fileservers automatically update their IP in
> the relevant places, that's why you almost always don't need
> the 'vos changeaddr' command.

Ah interesting, thanks.

>> [ ... ] What is the extra care for the elected master? [ ... ]

> Moving the elected sync site means that you will lose quorum
> for a minute or two, which means you can't write to the
> database. [ ... ] Note that a "client" in terms of ubik means
> not only kernel /afs clients, vos, pts, etc, but also
> fileservers. [ ... ]

[ ... ]

> If you want to know more about ubik in much more detail, to
> the level of distributed systems theory and stuff like that,
> there are a few papers on it floating around back when it was
> designed, I think. [ ... ]

I think I read some of those a long time ago, and I'll refresh
my memory, but my page of notes is quick hints of "peculiarities"
that need to be taken into account for system administration.

Currently IP issues are of particular interest because of
various datacenter and other changes there is one OpenAFS 1.4
3xdb 2xfs cell that I need to move to OpenAFS 1.6 on new servers
and new IP ranges, ideally in a rolling way, with minimal client
downtimes, because they clients are a set of web etc. servers
that have fairly high availability requirements.

So ideally I would be adding new AFS db servers and new AFS fs
servers, copying over db and volumes, and then retiring the old
ones smoothly, and thus my particular interest for the special
case for the elected master, to come up with a double-checked
plan.