How To Failover Mirrored database using Wizard and Auto failover

Operating mode Transaction safety Witness state
High-performance mode OFF NULL (no witness)**
High-safety mode without automatic failover FULL NULL (no witness)
High-safety mode with automatic failover* FULL CONNECTED

f the witness becomes disconnected, we recommend that you set WITNESS OFF until the witness server instance becomes available.

**If a witness is present in high-performance mode, the witness does not participate in the session. However, to make the database available, at least two of the server instances must remain connected. Therefore, we recommend keeping the WITNESS property set to OFF in high-performance mode sessions. For more information, see Quorum: How a Witness Affects Database Availability (Database Mirroring).