So why would you upgrade when your current HMC is working fine? For the same reasons you upgrade anything else -- for starters, faster CPU and better performance. The latest version of the HMC typically runs much faster than whatever you had before. Of course the other, more critical factor is that, over time, older HMC models are no longer supported. In any event, upgrading will happen sooner or later.
As the document notes, upgrading on the HMC isn't simply a matter of backing up one HMC and restoring it to your new one. You're basically clearing out your HMC and connecting a new console:
"This document describes the procedure for replacing an existing HMC. This procedure should be followed when 'upgrading' an existing HMC to a newer model/type. It applies to the situation where the new HMC manages the same server and may have the same IP address and host name as the HMC it replaces.
"If this procedure is not followed, some of the errors which may be encountered include the following:
o Open Serviceable Events which cannot be closed
o Platform Event Logs which are not reported or called home through Serviceable Events
o RMC communication problems between the HMC and partitions."
I'll preserve the meat of the information here in case the IBM link goes away in the future:
Before removing the old HMC:
1) Close all serviceable events.
a. Verify that all serviceable events reported against a managed server have been reported to IBM and repaired.
b. Close the serviceable events.
2) Permanently remove all server connections.
a. Record all current connections:
1. Access the restricted shell
Local HMC: Click HMC Management, Open Restricted Shell Terminal.
Remote: ssh to the HMC.
2. Run lssysconn -r all
3. Save the output.
b. Expand Systems Management, Servers.
c. For each server, remove the connection:
1. Select the server.
2. Expand Connections, select Reset or Remove Connections, select Remove Connection, click OK.
d. For each frame, remove the connection.
1. Access restricted shell
2. Run lssysconn -r all | grep type=frame
3. Record the IP address of the frame connections listed in the output. Example below: 172.16.250.255 and 172.16.255.251
lssysconn -r all | grep type=frame
4. For each listed IP address, issue the command: rmsysconn --ip <ip of frame> -o remove
Example: rmsysconn --ip 172.16.250.255 -o remove
3) Ensure all connections have been removed.
a. Access restricted shell
b. Run lssysconn -r all
c. Verify that there are no connections listed as shown in the example below:
lssysconn -r all
No results were found.
4) Remove the HMC.
Configure the new HMC:
Note: Restoring upgrade data or backup HMC data to a different model is not supported. A possible alternative is to use HMC data replication to replicate information onto the new hardware. Information that can be replicate includes: customer contact information data; user data (user profiles, task roles and resource roles); outbound connectivity configuration data.
Remember to periodically ask, is your firmware current? Is your HMC code current? Is your HMC model current? Is your VIO server code current? Are your OS images patched?
So are you ready to upgrade now? If not, what's holding you back?