HP OpenView Storage Mirroring High Availability for Exchange Server 2000/2003 Application Notes (May 2005, T2558-88020)

Storage Mirroring High availability for Exchange Server 2000/2003 application notes 23
The Windows Dynamic DNS (DDNS) client does not initiate a registration reflecting the
failed over name and IP address when failover occurs, and the ipconfig
/registerdns command will not cause the failed over name and IP address to be
registered. Accordingly, host records for the source will remain intact after failover and any
required changes must be made on all DNS servers used by relevant clients. Changes to
non-Windows DNS servers and Windows DNS servers with dynamic updates disabled
must be implemented by some other means, but since DNS zone files are text-based, they
can be manipulated with any scripting language that can open, parse, and write to a text
file.
c. Automated/Scripted updates using DNS WMI—The DNS WMI Provider can be used to
automate or script adding and deleting records to and from the DNS server. The steps vary
based on the operating system.
Windows 2000—For information on the DNS WMI Provider, visit
msdn.microsoft.com and
search for DNS WMI Provider. The following link can also be used:
msdn.microsoft.com/library/en-us/dns/dns/installing_the_provider.asp
To download the DNS WMI Provider, use the following link:
ftp.microsoft.com/reskit/win2000/dnsprov.zip
Once the DNS WMI Provider for Windows 2000 has been installed on the DNS Server, the
included VBS scripts can be used to automate DNS record modifications.
Windows 2003—The DNS WMI Provider is installed and configured by default on Windows
2003 DNS Servers, but the scripts necessary to modify DNS records are not pre-installed.
Windows Server 2003 users will still need to download DNS WMI Provider for Windows
2000, which can be found at the following link:
ftp.microsoft.com/reskit/win2000/dnsprov.zip
Dealing with a WAN failure
Just like the LAN environment, if a failure occurs and the Failover Control Center Time to Fail counter
reaches zero (0), a dialog box will appear in the Failover Control Center requiring user intervention to
initiate failover. Since your source and target servers are in a WAN environment, update your DNS
records on the target so that the source points to the target’s IP address. Then, acknowledge the manual
intervention prompt to start failover.
Again, like the LAN environment, the failover script created will automatically run. The target will have the
Exchange services started, the database mounted, and the user pointed to the target. If you did not script
DNS updates in the failover script, perform the manual DNS updates at this time. When those updates are
completed, clients can connect through Outlook or Outlook Web Access to receive their e-mail.
Recovering after a WAN failure
Follow the steps as outlined in ”Rebuilding the source” on page 14, noting that there is one additional
step. After step 1 and the source machine problems that caused the failure have been resolved, update the
DNS records so that the source name resolves to the original source IP address. All of the remaining steps
are the same for a WAN environment. When failback occurs, clients who were accessing Exchange on
the target at the time of failback may have to wait until their DNS cache is flushed and repointed to the
source, or they can force the flush by using the ipconfig /flushdns command.