depending on the operating mode and quorum of available nodes.
* Highly Available
In the highly available mode,
a full quorum is defined as the principal, mirror,
and witness being available and communicating with each other.
Figure 27-16 explains the recovery path depending on which server or servers are up and available.
If the principal is lost and the witness and mirror are available, then failover is automatic.
* High Protection
In the high protection mode,
a full quorum is defined as the principal, the witness
and the mirror being available and communicating with each other.
Figure 27-17 explains the recovery path depending on which server or servers are up and available.
If the principal is lost and the mirror is available,
then you have to manually fail the system over.
* High Performance
In the high performance mode,
a full quorum is defined as the principal and the mirror being available
and communicating with each other.
Figure 27-18 explains the recovery path depending on which server or servers are up and available.
If the principal is lost and the mirror is available,
then you have to manually fail the system over with possible data loss.
Source:
Microsoft SQL 2005 Administrator's Companion,
Chapter 27 - Log Shipping and Database Mirroring
Part VI - High Availability
Page 900-903