ER> This is more of a general question, but, is there a point to
ER> running a slave on the same hardware?
Yes. If you want a consistent backup of your data but still serve clients
while the backup is taken one might run a 'main' client-facing slapd
instance which is replicating to a 'snapshot' slapd instance. Each
instance has its own database backend subdirectory.
In normal operation the 'main' and 'snapshot' daemons run concurrently
with clients only connecting to the 'main' daemon. Updates are replicated
to the 'snapshot'. At backup time one cleanly stops the 'snapshot'
instance and takes a backup of the database backend by copying either the
raw database files or by running a slapcat. The 'snapshot' instance is
then restarted. Updates that occur on the 'main' instance while the
'snapshot' instance was stopped are resubmitted once the 'snapshot'
instance is restarted.