Hope,
In general, AFS does not work well when a server or client is
addressed through more than one network interface because each
interface has a distinct IP address. AFS uses the IP address of
clients and servers to keep track of volume locations, client callback
status, etc, and becomes confused when an alternate address is used
for a machine that it has already been in contact with.
Consider what would happen if you created a volume on a multi-homed
server having one host name but two IP addresses. The vos command
translates the given host name to an IP address which is stored in the
VLDB along with the volume name. If you later wanted to remove the
volume, you must again give the host name of the server. If the name
resolved to a different IP address, the vos command would report that
the volume wasn't found on the given host.
In some multi-homed networks, remote machines are able to reach only
one or the other of the interfaces. If volume were created by a
client using the first interface's IP address, the clients attached to
the second inteface would never be able to fetch the volume. It would
try to contact the fileserver using the IP address in the VLDB and
wouldn't be smart enough to try the alternate address.
A more drastic problem can result because of the callback system.
There are occasions where a fileserver will contact a client and
request that all callbacks for the fileserver be broken. Callbacks
are stored at the client by IP address, not host name, so some
callbacks for the server may be left intact. This can result in cache
inconsistencies when the client continues to believe that it has the
most up-to-date data.
At the present time, we suggest that AFS machines be given distinct
names for each interface and that only one interface be referenced
during AFS operations. In the future, we hope to enhance AFS by
providing support for multi-homed servers and clients.
Joe Jackson,
AFS Product Support,
Transarc Corp.
