[Pulp-list] pulp HA

[Randy Barlow]

On Tue, 5 Feb 2013, Steven Roberts wrote:
> I'm thinking active-standy wouldn't be too bad to do now.  use the
> Mongo replication features I have heard about and do an rsync of
> the /var/lib/pulp dirs.

I wanted to throw in a note here about Mongo's replication features. It
has a really nice automatic replication system where the various Mongo
nodes that are part of the replica set will vote on which one of them in
the master. The nice thing is that they are able to automatically handle
the scenario where the master disappears by revoting among the remaining
nodes to decide a new master. They will only do so if a majority of the
nodes are still able to be reached, otherwise they enter a read only
mode.

Because of this replication system, it is often recommended to install
Mongo servers in odd numbers. If you'd prefer to stay lighter on
resources, they also have a very thin system called an arbiter that
could be installed on a small system that only participates in voting.
With that, you could have two Pulp servers instead of the more typical
three.

For the /var/lib/pulp folders, an rsync setup could probably get the job
done. Alternatively, you might be able to use a shared filesystem, or
possible disk replication to accomplish something similar. I'm not sure
how much testing we've done with those sort of setups, so we'd love to
hear about it if you gain some experience in this area.

-- 
Randy Barlow