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Implementing the vHMC Requires Attention to Detail

December 4, 2018

If you're planning to get rid of your physical appliances and run all of the HMCs in your environment as virtual machines, keep this in mind:

Originally the IBM POWER HMC was sold only as an integrated appliance that included the underlying hardware as well as the HMC firmware. IBM extended the POWER HMC offering to allow the purchase of the traditional hardware appliance (e.g. model 7042/7063) or a firmware only virtual HMC machine image. The virtual HMC (vHMC) offering allows clients to use their own hardware and server virtualization to host the IBM supplied HMC virtual appliance.

Support for vHMC
Since the hardware and server virtualization is supplied by the client to run the HMC virtual appliance, this infrastructure that actually hosts the HMC virtual appliance is not monitored by IBM. Serviceable events related to the vHMC firmware are monitored however "call-home" for these events is disabled. For further information see document Callhome on HMC Serviceable Events is Disabled on vHMC ....

The HMC virtual appliance continues to monitor the managed Power Systems hardware just like the HMC hardware appliance. Both HMC form factors provide remote notification and automatic call-home of serviceable events for the managed Power Systems servers.

Support for vHMC firmware, including how-to and usage, is handled by IBM software support similar to the hardware appliance. When contacting IBM support for vHMC issues specify "software support" (not hardware) and reference the vHMC product identification number (PID: 5765-HMV).

How-to, install, and configuration support for the underlying virtualization manager is not included in this offering. IBM has separate support offerings for most common hypervisors which can be purchased if desired.

That document also includes a brief Q&A. I'll highlight the following, which often goes overlooked:

Q: Are there any restrictions related to on-site warranty support for managed servers?
A: Restrictions are similar to the hardware appliance
- You must supply a workstation or virtual console session located within 8 meters (25 feet) of the managed system. The workstation must have browser and command line access to the HMC. This setup allows service personnel access to the HMC.
- You should supply a method to transfer service related files (dumps, firmware, logs, etc) to and from the HMC and IBM service. If removable media is needed to perform a service action, you must configure the virtual media assignment through the virtualization manager or provide the media access and file transfer from another host that has network access to HMC.
- Power vHMC cannot manage (nor service) the server it is hosted on.

The big takeaway is that you shouldn't assume IBM service reps will plug into your customer network to access your virtual HMC. If you need assistance, IBM expects you to provide a workstation that they can access. And yes, this can be problematic. Worst case: some sort of outage is affecting your VMware cluster while IBM Support needs to work on your POWER hardware. Then you might end up in a pickle.

Incidentally, this is one significant point in favor of the traditional HMC form factor. It takes up 2U in your rack and it exists solely to manage your machines. Nonetheless, people will continue to move away from hardware-based HMCs, so it's important to understand the requirements. While I prefer keeping a hardware appliance available and using the vHMC as a backup, of course every environment is unique. Only you know what will work best for you.

Posted December 4, 2018| Permalink