[infinispan-dev] Use cases for x-datacenter replication

[Dan Berindei]

On Mon, Feb 13, 2012 at 11:16 PM, Erik Salter <an1310 at hotmail.com> wrote:
> - My comment about a quorum has to do with the physical network being down
> between data centers in a virtual cluster scenario.  In my use case, the
> clients would only be able to talk to their local data centers anyway.  If I
> have appropriate coverage on my local site (and any other data center I'm
> connected to), I don't necessarily want to start a state transfer.  Any
> deltas can be pushed to the other sites when they come back online.
>

Erik, bringing up the connection between two datacenters would trigger
a merge, not a join.
So each datacenter will think it is the "old" primary owner of the
data, and the backup site will try to overwrite the data in the
primary site.

In order to handle this case we also need a versioning scheme that
rejects outdated data from the backup datacenters and instead updates
the backups' data with the primary's values. (Of course, to make
things more complicated, in your scenario each datacenter is primary
for one slice of the data and backup for another slice.)

Cheers
Dan