The IBM Hardware Management Console is used for, as the name implies, managing the hardware of IBM systems, including IBM AS/400, IBM System p, IBM System z, and IBM Power Systems. As this is the AIX Museum, we are primarily focused on the HMC’s interaction with older POWER systems.
There is a relatively complex support and compatibility matrix between 1) HMC hardware, 2) HMC software, and 3) POWER server firmware versions. Determining the correct combination can be quite the challenge, as there are usually many differing requirements and conditions that force the decision to go one way or another. The IBM Fix Level Recommendation Tool (or FLRT, sometimes just referred to as ‘flirt’) can help tremendously with this task.
IBM’s “POWER Code Matrix – Supported HMC Hardware” document is probably the best for understanding the relationship between HMC hardware, HMC software, and POWER server support. IBM’s “HMC and System Firmware Supported Combinations” document covers the various combinations of HMC software and supported POWER server firmware.
As one would expect, there are a myriad of reasons to run one version over another, with implications of support or compatibility when you make one choice or another. Sometimes your HMC is getting old, and it isn’t in the budget to get a new one, your old HMC can only run certain versions of the HMC software, which then in turn limits the firmware that you can run on the POWER server itself, which then limits what POWER servers you can use with the HMC.
Sometimes you’re forced to take a firmware update on a POWER server when you’re doing a hardware upgrade, which then requires the HMC to be running a particular version of the HMC software, which can then require the HMC to be running on a particular version of the HMC hardware. Sometimes there are known issues in the HMC software, forcing an upgrade. Sometimes you buy new POWER servers and they can’t be managed by your old HMC, so you now have two HMCs that don’t talk to each other. All kinds of things can cause that matrix to be complicated.
Back to Reality
However, the average /r/homelab user generally gets their hardware at, near, or after its end of life. Concerns about IBM support, firmware versions, etc. are no longer issues. Generally there is no support, and generally the firmware is at or near the last released firmware for the system.
And, probably most importantly, the average homelab user probably isn’t running a physical HMC. There is very little reason to run a physical HMC for most homelab users, generally only if you need physical serial interconnects for the POWER servers, or you are specifically interested in working on the HMC itself. Removing the limitations of the actual HMC hardware makes the compatibility matrix much easier to work with. So that support matrix usually boils down to: run the newest compatible HMC major version and you’ll be fine.
A good rule of thumb for older POWER systems is to just pick the HMC software version based on the POWER processor you have. So, without further ado:
- Run HMC v9 for POWER9 and POWER8
- Run HMC v8 for POWER7 and POWER6
- Run HMC v7 for POWER5
- Run HMC v3 for POWER4
For example, my 8204-E8A Power 550 Express system, with a POWER6 processor and running the ‘EL350_172’ firmware, is supported by the IBM HMC V7R350 software, all the way through V8 R870 SP3. Seventeen distinct HMC software versions! (Details found here.)
On the HMC hardware side, the V7R350 software is supported on the 7310-C03 HMC, and the V8 R870 software is supported on the 7063-CR1 (ppc) HMC. A whopping nineteen distinct HMC hardware versions. (Details found here.)
Now I also have a POWER7 system which is supported by HMC software v7 all the way through V9 R2, and again on the hardware side that V7 through the V9 software is supported on all HMCs between the 7042-C08 HMC, and the newest 7063-CR2 HMC. Only 9 HMC models this time. (Again, details found here.)
So what did I choose? Since I wanted to run the newest supported HMC software version by my old p6 system, I run the v8 R870 SP3 HMC software in a virtual machine (roughly) emulating the hardware specs of a 7042-CR6 HMC. Both the p6 and p7 systems can live within the same HMC, and the HMC itself is relatively lightweight.
Some notes:
- Sometimes you have to use the WayBack Machine to find details that have fallen off of IBM’s website.
- Realistically in 2024, obtaining a p10 is extremely unlikely, so we will ignore those.
- Similarly, while HMC software v10 does support p10, p9, and p8, it is quite new and in active development, so we’ll ignore it.
- p3 and lower didn’t use an HMC (as we know it), so we’ll ignore those.
- HMC software v4 and v5 didn’t offer any advantages over v7, so we’ll ignore those.
- There is no link between server firmware or HMC, and AIX.
- Generally, server firmware lists minimum HMC requirements.