Re: HMC as a Power lpar?

In the Chicken and Egg game the Physical HMC came out first the Virtual HMC came out a couple years ago - Just to set the start point.

The virtual HMC does not need Windows in any way. It runs on either KVM or VMWare and those are both linux based. I suppose you could run it as a VM on a Windows Workstation but that doesn't make sense to me in a DC environment.

From a pure capability standpoint I don't think it matters one way or the other. I use both virtual and physical HMCs and I have found nothing that one will do that the other will not. One difference during updates of the HMC itself though is the pHMC takes FOR-EV-ER to reboot after each update as it plows through all the server's UEFI boot up logic. (Note: this may be a spot where the Power HMC is better, yet to be known) The vHMC reboots fantastically quicker at it doesn't have to waste time with the pre-o/s UEFI bootup stuff. Advantage vHMC. Also if there is some issue with the HMC that requires use of it's actual console VMWare provides very nice remote console to that while IBM tells you NOT to use the service port on the pHMC for some odd reason. Second advantage vHMC. And the vHMC is much cheaper and takes no rack space. That's vHMC for the win 3 to 0.

However the biggest draw to a pHMC for me is in a disaster situation or just to be un-joined with the x86 virtualization side of your DC. If you are working to get infrastructure up after a full DC shutdown and you're in a hurry you can power up the pHMC and get after the work of bringing up your Power Systems. Meanwhile your vHMC may be waiting on storage to start and then storage networking (Fiber etc) and then networking and then the virtualization platform and finally your vHMC is ready. In your environment this may not matter to you, or it could matter a lot, as we consultants like to say: "It Depends." :-)

As to HMC better than front panel Hex Codes, um, yeah... First off there is SO much you can do with an HMC that you cannot do with the front panel or even combinng that with ASMI. So Win for HMC there. Second my HMCs are NOT just a few steps away and in fact I've probably worked on more than a dozen of them that I've never even seen. Given the choice to go HMC or no HMC that's not a choice. Get an HMC.

- Larry "DrFranken" Bolhuis

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On 8/9/2017 4:36 AM, Jonathan Wilson wrote:

On Tue, 2017-08-08 at 11:08 -0400, Rob Berendt wrote:

First let me say that I know very little about the HMC, so the following
may sound like stupid questions...

Is a hardware HMC any different to a PC running a virtual HMC? Is the
hardware HMC just a case of just buying the "virtual" HMC software
pre-loaded on a bit of hardware as the host/bare metal OS without
needing windows(1) and/or a "virtual box" client OS (running the HMC
software)?

(1) Does the virtual HMC even need windows? Can it not be run under
Linux? (I vaguely recall reading that it uses VMware or something
similar, so I'd assume if that were the case it could run under any OS
that could host a virtual box that ran the software.)

If the virtual HMC is nothing more than an emulated set of hardware, and
the OS that runs the HMC software that resides on a hardware HMC... then
running the virtual HMC on a power hardware system wouldn't be that
difficult. Further, if it could emulate an X86 machine it wouldn't
require re-compiling the HMC software, but obviously there is then a
chicken and egg situation if the virtual HMC is the HMC of the hardware
on which it is installed if you only have one physical box (but then
isn't it possible to buy a power system that doesn't have any kind of
HMC as its also possible to do some "low level" maintenance/management
stuff by entering hex codes on the font panel? The HMC just makes it
more convenient/easier/remoteable?)