The connected POWER systems can be completely managed by the HMC. All possibilities of the PowerVM virtualization can be configured and administered using the connected HMCs. POWER systems connected to an HMC are also referred to as so-called managed systems, since the HMC ‘manages’ these POWER systems. In the following we will mostly use the term managed system instead of POWER system, in both cases the physical server is ultimately meant.

The HMC offers two different administration options:

• • A web-based GUI: access is via a browser.
  • And a CLI on the HMC: access is typically via a login using OpenSSH.

Typically, most users use the web GUI. It is intuitive to use and all activities can be carried out using the GUI.

Only a few users use the CLI. The syntax of the commands is not always that simple and very long commands with many options quickly have to be used even for smaller tasks. This usually requires to look through the documentation frequently, as many options are very difficult to remember. Most of the time, however, every POWER administrator has a small set of CLI commands that he uses regularly, as this is often faster than using the GUI.

The LPAR tool uses OpenSSH and the HMC’s CLI. As a rule, you do not have to specify any options, as the LPAR tool automatically specifies the necessary options.

The following account is available on an HMC by default:

• • hscroot with password ‚abc123‘.

This account has the role hmcsuperadmin and thus has the maximum (almost) of rights on an HMC. Additional accounts can (and should) be created for users. We will go into more detail on the topic of HMC accounts and roles later, for the moment we assume that either an account for the user already exists or the hscroot account is used.

The HMCs known to the LPAR tool can be listed with the “hmc show” command:

$ hmc show
NAME SERIAL_NUM TYPE_MODEL
$

If no HMC has yet been registered, the output is empty, as in the example output above.

Each HMC must be registered once for use with the LPAR tool. This is done with the “hmc add” command by specifying one or more HMCs. In our example the HMC registered is called hmc01:

$ hmc add hmc01
hmc01: 
   ms01
    > lpar01
    > ms01-vio1
    > ms01-vio2
   ms02
    > aix01
> aix03
> aixnim
    > ms02-vio1
    > ms02-vio2
   ms03
    > aix02
> aix04
    > ms03-vio1
    > ms03-vio2
$

Registering an HMC typically only takes 1 or 2 seconds. As can be seen from the example output, the connected managed systems and the LPARs on the managed systems are recognized and also registered. The 3 managed systems ms01, ms02 and ms03 are connected to our HMC hmc01.

If only the name of the HMC is specified for “hmc add“, the LPAR tool assumes that the account on the HMC corresponds to the local user name. If this is not the case, the desired account can also be specified explicitly, as in the following example:

$ hmc add hscroot@hmc01
hmc01: 
   ms01
    > lpar01
    > ms01-vio1
    > ms01-vio2
   ms02
    > aix01
> aix03
> aixnim
    > ms02-vio1
    > ms02-vio2
   ms03
    > aix02
> aix04
    > ms03-vio1
    > ms03-vio2
$

This means that the hscroot account will always be used for the specified HMC.

All other HMCs should then be registered once in the same way.

Now that at least one HMC has been registered, it can be displayed using “hmc show“:

$ hmc show
HMC   SERIAL  MODEL
hmc01 12BEEF  7042-CR9
$

Our HMC has the serial number 12BEEF and is of the type 7042-CR9 (this is the last model based on x86).

If an HMC, including the connected managed systems and their LPARs, is no longer to be managed by the LPAR tool, the HMC can easily be deregistered. For this purpose the command “hmc remove“ is used:

$ hmc remove hmc01
$

Of course, this does not change anything about the HMC, one of the connected managed systems or one of the LPARs! It just means that the HMC is no longer known to the LPAR tool. The attempt to address the HMC with the LPAR tool results in a corresponding error message:

$ hmc lssysconn hmc01
ERROR: hmc01 is not a known HMC
USAGE:
   hmc lssysconn [-o <format>] [{-f|-j|-y}] [-F <fields>] [-s <selections>] [-v] <hmc>
$

Of course, the HMC can be registered again at any time using “hmc add” and can then be administered again using the LPAR tool.