When using a shared store, both the live and backup servers share the same, entire data directory, using a shared file system. This includes the paging directory, journal directory, large messages, and the binding journal. When failover occurs and the backup server takes over, it will load the persistent storage from the shared file system. Clients can then connect to it.
This form of high-availability differs from data replication, as it requires a shared file system accessible by both the live and backup nodes. This will usually be a high performance Storage Area Network (SAN) of some kind.
The advantage of shared store high-availability is that no replication occurs between the live and backup nodes. This means it does not suffer any performance penalties due to the overhead of replication during normal operation.
The disadvantage of shared store replication is that it requires a shared file system, and when the backup server activates it must load the journal from the shared store. This can take some time, depending on the amount of data in the store.
If the highest performance during normal operation is required, there is access to a fast SAN, and a slightly slower failover rate is acceptable (depending on the amount of data), shared store high-availability is recommended.