Comparison of Different Solutions
- Shared Disk Failover
Shared disk failover avoids synchronization overhead by having only one copy of the database. It uses a single disk array that is shared by multiple servers. If the main database server fails, the standby server is able to mount and start the database as though it were recovering from a database crash. This allows rapid failover with no data loss.
Shared hardware functionality is common in network storage devices. Using a network file system is also possible, though care must be taken that the file system has fullPOSIX behavior (see Section 17.2.2). One significant limitation of this method is that if the shared disk array fails or becomes corrupt, the primary and standby servers are both nonfunctional. Another issue is that the standby server should never access the shared storage while the primary server is running.
