HP StorageWorks Storage Mirrioring Application Manager user's guide (T2558-96322, April 2009)

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8. Click the Test button to validate that DNS failover is configured correctly for the selected DNS
server(s) and that the specified credentials are sufficient to update DNS.
9. When the DNS configuration is complete, click OK to save your entries and return to the
Configure Protection window.
Identity failover
Select this option if you want to failover by transferring the source IP address 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.
In Identity Failover, the target’s physical identity is modified to match the source during a failover.
This includes the target adopting the source server’s name, primary IP address, and drive shares
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 have client applications that are configured to connect to an IP address rather than a server
name.
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 /? from a command prompt.
NOTE: 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.