Comment 5 for bug 1182094

This will be applicable in
a) When there is an existing datadir and node has been down for
sometime (so out of date, requiring a SST).

b) When there is a prepared backup lying on the host (used to
create the node) and that be reused.

The joiner sends LSN to donor the way uuid:seqno are sent. To obtain
LSN, currently, mysqld needs to be run with wsrep-recover or so. Note,
that this applies only when using pre-existing datadir, otherwise
xtrabackup_checkpoints file can be reused. The donor then creates the
incremental stream and sends to joiner. The joiner needs to apply this
delta to the pre-existing backup and use it. Also, note that, the
pre-existing backup on joiner needs to be apply-log-only prepared.