HP Storage Mirroring V4.5 Software - Manual (Page 29)

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7. In the Password field, enter the password that will be used to access/modify DNS records.
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.
In order to set the primary DNS server with which the Application Manager will communicate during
failover, you must launch Application Manager using the command line
/exchange /advanced
option (
dtam /exchange /advanced
). When launched in the Advanced context, the Client DNS
Server field will appear on the Configure DNS Failover window. Use the Client DNS Server field to
select the primary DNS server.
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 your Exchange server is using a public IP address to receive email, you will have to
change the public advertised DNS MX record to reflect the target IP. Consult your
service provider for instructions.

To allow external email to be delivered to the target server when the source is
unavailable, you should create an additional external MX record for the target server.
The target MX record should have a lower priority than the source. Refer to your router
or firewall documentation for more information.

For more information about using the DNS Failover utility, access the
dfo.exe
help by
typing
dfo.exe /?
from a command prompt.
NOTE: Identity failover is not supported in clustered environments.
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.