[OpenAFS] Migration from Transarc to OpenAFS

[Jeffrey Hutzelman]

Yes; by "too old" I meant servers so old the VLDB format had changed (you don't need to worry much about the PRDB; except for supergroups (enabled only if you configure it in), that hasn't changed in a _long_ time).

It is entirely safe to mix old and new fileservers, though if you enable largefile support then any volume which actually contains a large (>2GB) file cannot be moved to an old server, or restored onto one.

You certainly can add dbservers and then remove the old ones, but to do that you need to be careful about configuration -- the CellServDB files must agree on all db servers, and a restart is required to notice the changes.  Also, if a server is elected as coordinator that does not appear in the clients' CellServDB's, then clients will be unable to perform operations which change either database, including creating and manipulating users and groups as well as most volume admin operations.  When we set up new dbservers, we added them in advance as non-voting servers, so they wouldn't affect quorum and couldn't be elected, then switched the config (carefully!) to make them voting once they were stable and the client CellServDB changes had made it out.

--Jeff