[OpenAFS-devel] Ubik voting idea

[Ted McCabe]

Situation:
   For some time now, I've seen/heard occassional discussion over how 
to possibly address the situation where the maintainers of a cell 
prefer their sync-site to be some server that doesn't have the lowest 
IP address.  Every solution I can recall has an ordering preference 
on each server for who they would vote for.
   While relatively straightforward to implement, I've not seen a way 
to deal with servers configured with different vote ordering 
preferences.

Idea:
   Modify the ubik voting scheme so that the voting is no longer for 
sync-site, but instead is for the designator of the sync-site.  The 
current method of voting remains unchanged, only the "office" changes.
   The designator would choose the sync-site based on its own 
configured preferences from those servers it knows are available to 
be sync-site.  Those preferences may indicate that the designator 
names some other server to be sync-site.

   With this scheme, there is no longer any concern for db servers 
having different notions of which servers are preferred for sync-site 
since only one sync-site ordering is used.  In fact, the cell 
maintainers would be free to give servers different preferences for 
sync-site.

Thoughts?  Concerns?

Additional idea:
   Perhaps also possible, the designator's preferences may specify 
that a server (or servers) is so strongly preferred for sync-site 
that the designator may change the sync-site even if the current, 
not-so-strongly-preferred sync-site is still functioning as such.
   I expect if this idea has merit, it would only be implemented after 
the first has proven successful but still not sufficient.  My main 
interest for comments is thus on the first idea.

    --Ted