HMCs and system parameters

Determining the HMC(s) that Manage a Partition

A Linux on POWER question I frequently hear: How can I find out the hostname or IP address of the HMC that is managing the partition I’m currently using?

A partition can be managed by up to 16 HMCs at a time (I usually only see 1 or 2 managing a particular system, but the option for more is there). The HMC connection information is stored by the platform, and exposed to the partitions as system parameters. These system parameters can be viewed (and sometimes modified) by using the serv_config command (serv_config is “serviceability configuration”, not “server configuration” or some such). As root, run:

/usr/sbin/serv_config -e hmc0

through

/usr/sbin/serv_config -e hmc15

to check each of the possible HMC slots. Many of the slots will be empty, returning no information. However, each slot which currently contains HMC connection information will return a string like the following:

HmcStat=1;HscName=eserver xSeries 335 -[7310CR2]-*105FB7A;
HscHostName=hmc-hostname.ibm.com;HscIPAddr=1.1.1.1;HscAddIPs=1.1.1.1;
CredID=;RMCKey=;RMCKeyLength=8;

HmcStat=1 indicates that an HMC is currently active (if the HmcStat value is some other value, the partition is not currently using–or in touch with–the HMC in that slot). Note that HSC is an older term for HMC: “Hardware Service Console” instead of “Hardware Management Console”. Any time you see HSC, think HMC.

The serv_config utility is part of the powerpc-utils-papr open source package, which is sometimes renamed by distributors in their products:

  • RedHat combines the powerpc-utils package with powerpc-utils-papr into a package called ppc64-utils.
  • SuSE also combines powerpc-utils with powerpc-utils-papr, and calls it powerpc-utils.
  • Gentoo provides the packages as ibm-powerpc-utils and ibm-powerpc-utils-papr.

Viewing/Configuring Other Serviceability Parameters

There are a number of other interesting variables that can be viewed and/or modified with serv_config:

  • serv_config -e partition_auto_restart: determines if the partition will automatically restart after an abnormal termination (like a kernel panic). Read/write; possible values are 0 or 1.
  • serv_config -e platform_auto_power_restart: determines if the platform restarts automatically after a loss of power. Read/write; possible values are 0 or 1.
  • serv_config -e platform-processor-diagnostics-run-mode: configures the schedule the platform uses for running automatic processor diagnostics. Read/write; possible values are 0 (disable processor diagnostics), 1 (stagger diagnostics so that only one processor is diagnosed at a time), 2 (immediately diagnose all processors), or 3 (diagnose processors on the schedule determined by the hypervisor).
  • serv_config -e sp-current-flash-image: which of the two firmware banks is currently booted? Read only; 0 indicates that the permanent side is booted, and 1 indicates that the temporary side is booted.
  • serv_config -e platform-dump-max-size: specifies the maximum filesystem space that can be used by platform (hypervisor, service processor, etc.) dump data. Read only.

An important note: not all systems and configurations will provide all of the possible parameters. To set one of the read/write parameters, use the following syntax: serv_config -e <parameter>=<value>.

There are a number of other parameters that control service processor features such as surveillance, call home, wake-on-LAN, remote power-on, etc. These can be a little more complicated to configure, but serv_config provides a simple command-line interface for configuring them. Run man serv_config for more details.

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