[OpenAFS] Re: Questions about multihoming servers

[Andrew Deason]

On Wed, 25 Sep 2013 00:03:12 -0400
Jeffrey Altman <jaltman@your-file-system.com> wrote:

> DB servers do not have UUIDs but more importantly the UBIK database
> replication protocol has no support for them or any other mechanism that
> could associate more than one IP address with a single service.  From
> the perspective of UBIK and all of the DB server clients, each IP
> address is a distinct server.

This is completely false. Or I'm misinterpreting what you're saying, but
I don't see what I could be misinterpreting about this. While there are
no UUIDs in ubik, it certainly does have a mechanism for matching
different IPs to a single service; each site broadcasts its list of
interfaces via DISK_UpdateInterfaceAddr to all other sites, so that
sites can map an incoming RPC IP to a specific site (via
ubikGetPrimaryInterfaceAddr). Instead of having a UUID to identify a
site, we can identify it by its "canonical" IP, which is the IP in
CellServDB.

If a voting ubik node has IPs 198.51.100.2, 3, and 4, with 2 in the
cellservdb, any node is supposed to interpret a request from e.g.
198.51.100.3 as coming from 198.51.100.2. That is, at the ubik layer,
for ubik voting purposes; not e.g. at the rx layer.

Now, if it's broken, it's broken, and 15640 sure makes it looks like
it's broken at least with netinfo. But the underlying infrastructure and
capability is there.

-- 
Andrew Deason
adeason@sinenomine.net