[OpenAFS] Re: Change the IP of a Cell server

[Andrew Deason]

On Thu, 14 Feb 2013 15:55:54 +0000
"Edgecombe, Jason" <jwedgeco@uncc.edu> wrote:

> I know that I need to push out a new CellServDB to the servers and
> clients, but what is the best procedure? Do I need to restart all of
> my AFS servers? What will be the impact if I  don't touch  the
> non-rehosted file servers and let them perform a service restart as
> part of the weekly restart?

The impact for not restarting the fileservers is about the same as not
modifying the client server list. A fileserver may try to contact the
old 'bad' IP, the request will timeout, and it will failover to one of
the other sites.

For (unix) clients, you can just modify the client server list before
the IP changes, or after. Either way, when a client has a 'bad' IP in
its server list, it may try to access that site; it'll appear to hang
until the request times out, and then it should failover to one of the
other sites.

If you want to avoid the possible hang in the client, you can do that if
you treat the IP change as two separate events: removing the old
dbserver, and adding a new one. You can do something like this:

 1. Remove the old IP from clients (fs newcell)
 2. Change the IP and restart the dbservers
 3. Add the new IP to clients (fs newcell)

If you want to be really really sure nobody is still pointed at the
'old' IP before you switch it, you could try to look for accesses
between steps 1 and 2 above. You can either look at network traffic, or
turn up the debugging in the ptserver/vlserver.

-- 
Andrew Deason
adeason@sinenomine.net