Database mirroring is a technology used for both high availability and disaster recovery, which allows for rich configuration. Mirroring uses up to three server roles:
- Principal
- Mirror
- Witness
The principal server holds the database that is mirrored. This database has to be configured with Full Recovery model in order to participate in the mirroring configuration. The mirror server holds a mirrored copy of the database, but unlike replication or log shipping, this database is not available for user access. The witness server can be configured in case you would like to utilize automatic failover of the mirrored database between the principal and mirror server due to unavailability of the principal.
Database mirroring operates in three modes. Each mode has its advantages and disadvantages and it's important to understand these in order to choose the right...