HP Storage Mirroring V5 Software - Manual (Page 54)

44 Protecting a SQL Server
NOTE: If you are running Windows Server 2000 on the primary DNS server hosting zones or domains that
contain source and/or target resource records, you must have the DNS WMI Provider installed on that DNS
server.
The Dynamic updates setting for the DNS zone should be set to Secure only . Otherwise, you must disable
dynamic registration on the source server in order to prevent the source from reclaiming its DNS record.
If a hosts file entry for the source server exists on the client machine, errors may occur during a failover and
failback.
Reverse lookup in DNS should be enabled. For more information about enabling reverse lookup, refer to your
Microsoft documentation.
DNS registration for the private (devoted to Storage Mirroring) NIC IP should be disabled.
If dynamic updates are enabled on a standard primary zone, the source server will be able to update its DNS
records after failover. To prevent this, configure DNS to use an Active Directory-integrated zone.
For more information about using the DNS Failover utility, access the
dfo.exe
help by typing
dfo.exe /?
.
Identity failover
Select this option if you want to failover by transferring the source IP and name to the target. When using
identity failover, it is possible that a name and/or IP address conflict can occur either during failover or when
the original source server comes back online. To avoid this conflict, use DNS Failover .
NOTE: Storage Mirroring Application Manager cannot be used for failover or failback when the Identity
failover method is selected. (However, the Failover Control Center can still be used to initiate failover). DNS
failover reduces downtime and provides other benefits. It is recommended for most environments.
In Identity Failover, the target will adopt the source server’s name, primary IP address, and drive during a
failover. Identity failover may be required in the following situations:
• Access to the domain controller or DNS server is not available (for example, due to permissions) from the
account that Storage Mirroring runs under on the source/target servers.
• If you determine that the time it takes to propagate the necessary DNS or Active Directory changes to the
rest of your environment is not acceptable. The time needed to propagate these changes depends on your
Active Directory Replication and DNS server settings.
• If you want to failover shares from the source to the target.