HP StorageWorks Storage Mirroring application notes Guidelines for networking and failover (T2558-96063, February 2008)

Storage Mirroring Guidelines for networking and failover application notes 9
Failover and DNS
DNS resolution is also a consideration after failover, especially when the source IP address is not failed
over to the target. Use the following decision tree to determine when DNS host entries need to be changed
after failover.
DNS failover using the DNS Failover utility
Downloading the DNS Failover utility (dfo.exe)
The DNS Failover Utility (DFO.exe) is available for download to provide a method of failing over DNS
records.
1. Go to the HP StorageWorks Storage Mirroring product page website:
http://h18006.www1.hp.com/products/storage/software/sm/index.html
and click Support and
documents.
2. Select your product, click Download drivers and software, choose your operating system and then scroll
down to the DNS Failover utility.
3. Click Download.
Running the DNS Failover utility
1. Extract the DNS Failover utility to the Storage Mirroiing proram directory on the target server.
2. Start a command prompt. Change the current directory to the Storage Mirroring program directory,
then run the following command to register the
CAPICOM.DLL file:
Regsvr32 capicom.dll
3. Create a user account with the following permissions, which are required to use the DNS Failover Utility
to modify DNS records:
Do clients use
No
Yes
DNS scripting is not required.
Since no clients use DNS to resolve the source host
name, there is no need to make any changes after
Is the source
DNS scripting is required.
DNS must resolve the source host name to the
primary target IP address after failover to ensure
operability of client/server NetBT communications
Are the target
DNS scripting is required.
DNS scripting is not required.
Since Windows 2000 client/server communication can use
SMB/IP on TCP port 445 on all IP addresses, there is no need
to make any changes after failover.
DNS to resolve
server names?
failover.
IP address failed
over to the
target?
No
Yes
on port 139.
server and all clients
Windows 2000
or later?
No
Yes