Informing the IBM Community

A Screen a Story – to desire or to require


You may think that a Hardware Management Console (HMC) is a luxury that is only needed by larger POWER user environments but in this article I am going to try and explain why you should think again.

A LAN console may be technically sufficient for your needs and does not put much weight on your      wallet but during my years as a systems administrator I have learned the hard way that there is not a better way to manage IBM i LPARs than with a Hardware Management Console (HMC).

In this article I would like to discuss one of the aspects of the benefits of an HMC which is a little bit under the radar. It is about the assignment of PCI adapters (or slots) to an LPAR.

When a POWER system is shipped to a customer all resources available in the box are assigned to the only LPAR running on the box. If your system is shipped with a physical HMC or a virtual HMC (vHMC) this still can be the case. Although you may never want to add another LPAR on the system, I hope the information in this article will make you decide to change that.

The screen below shows the physical I/O Adapter assignment of an LPAR profile:

As you can see all adapters are added as Desired, instead of Required. Some say that Desired is the wrong option because the system will not start without the load source being Required but, in this case, only one LPAR is running on the POWER system, so who else could use it? 
Anyway, this is a subject that is best discuss over a pint in a bar, you provide the beer and I will provide the discussion 😉      

At the moment 4 slots are assigned which are empty. Assigning empty slots, that seems a bit silly, it is like I am giving you nothing. The good thing is that empty slots can be filled with an adapter and this is where the rich functionality of the HMC steps in.

If you select the “all systems option” on your HMC and select a system by pressing the blue line beneath the image of a Power server, a menu bar pops up in your screen. Below the menu “Serviceability” is the option “Serviceability”. When selecting that one, a new screen is shown with the option “Add FRU”. FRU stands for Field Replaceable Unit.  In this case an FRU could be a new PCIe adapter card and yes you can add or remove it whilst the system is in use!

This sounds somewhere between scary and impossible but don’t worry, when selecting that option you are taken by the hand and guided by the HMC through every step, explaining w when and how to do it.

As we all know down time is a big thing in today’s world so concurrent maintenance will avoid having to shutdown applications. In some cases, an unassigned slot, like an empty slot, gives you the option to add an adapter without having to shut down your system. This is only possible when you have an HMC, your Ops Console cannot do this for you.

ProTip Even if you don’t have the need to add a new adapter card, if you have a HMC, then should you have a problem with one of your existing FRUs the IBM engineer would be able to take advantage of this “hot swap” feature to fix your system without down time.    

     So, the next time you configure an LPAR profile on your HMC, please be aware that assigning empty slots does not really add anything, but if you do, please use the desired option. This will allow you to remove it from a running LPAR and with concurrent maintenance as an option, allows you to add an adapter without down time. If you accept the challenge to do this is entirely up to you, just follow the instructions given by the HMC.

This link will show you that AIX, IBM i and Linux LPARs all allow you to do concurrent maintenance, below an image from the link:

The decision to go for concurrent maintenance can be a daunting one, but since it is offered it must for sure have been thoroughly tested by IBM. With an HMC you now have the option, that is what I call luxury.


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