ValidatedMember indicates how the mirror member determines its role before joining the mirror.
1 (true) - The instance joins the mirror in its current role.
0 (false) - The instance contacts the primary to obtain its current role before joining the mirror. Use this when there have been role changes within the mirror while the instance and its ISCAgent were down or unreachable. For example, if a DR async has been promoted to backup while the former backup was down, set ValidatedMember to 0 before restarting the instance to ensure that the former backup receives its new role of DR async from the primary before restarting the mirror.