Whats available for doing near-realtime master->slave file replication between two CentOS systems?
Cronjobs running rsync won't cut it.
Ideally, I'd like something that works like SLONY-I does for Postgres databases, where all file system block level transactions on the master get replicated to the 2nd system on a 'as fast as practical' basis (a second or two of lag is acceptable). If the slave is offline or connectivity is interrupted, these transactions should be journaled so they can be played back when things resume.
I'm open to other approaches, so far I've found very little in this category... I briefly considered using LVM mirroring over iscsi to the slave, but A) this is synchronous, B) recovery from a service interruption would require remirroring the whole volume.
I've been reading about GFS but am somewhat confused as to its capabilities. The examples given on redhat's pages seem to involve shared storage (SAN or whatever) and distributed cluster access, I don't need any of that, just simple master->slave one way asynchronous replication.