Understanding Operating Modes
There are essentially three operating modes for database mirroring, as follows:
• High-safety mode (synchronous)— After a database mirroring session is initiated under high-safety mode, the mirror server database synchronizes with the principal server database and then writes the logs to disk. After the logs have been written to disk, all transactions are committed on both servers. Although this mode guarantees no data loss between the two servers, it does come with the expense of increased transaction latency.
• High-availability mode (synchronous)— Also referred to as high-safety mode with automatic failover, this operating mode is made available only with the presence of a witness server. This mode is the recommended ...