[OpenAFS] What happens if a client doesn't see a "break callback" caused by a volume move?

[Jeffrey Altman]

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Kim Kimball wrote:
> Hello folks,
> 
> Given:
> 
> a. A volume is moved
> b. The moved-from fileserver breaks all callbacks for that volume.
> c. A given client does not see the break callback message.
> 
> What happens?
> IIRC the file server puts the client on a "client down" list and ignores
> the client until the client contacts the file server again.  The client
> is oblivious to changes in the volume, but may eventually contact the
> moved-from file server again and 1) be told to break all callbacks for
> volumes on the file server and 2) that the moved volume is no longer
> available on the moved-from fileserver.

Correct.

> I also believe that there are timeouts on cached VLDB information, 60
> minutes IIRC, and that the cached volume information should expire and
> the client should go back to the vlserver to refresh location info for a
> given volume, thereby discovering within 60 minutes that the volume was
> moved.

The Windows client invalidates all server lists once per hour.  It does
not maintain a per volume expiration timer.

> Could someone please either shoot my theories full of hooools (as one of
> my ESL students once said) and/or fill in the blanks?

The one thing to keep in mind is that the server list invalidation does
not invalidate the callback.  So if the callback on the volume is good
for two hours the client is not going to attempt to access the volume
server list again until the callback expires after two hours.

Jeffrey Altman
Secure Endpoints Inc.



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