A managed system is not a UNIX system, no daemons (like ntpd) can be started. Although there is the POWER Hypervisor as a software component, it has the task of managing access to the physical resources and does not support any services such as NTP. The configuration of a time synchronization must therefore be done in a different way, which is shown below.

Time reference partitions (TRP) can be used to synchronize the time of the POWER hypervisor and service processor(s) on a managed system. An LPAR becomes a Time Reference Partition (TRP) by setting the attribute time_ref to the value 1. Only LPARs that are not moved to another managed system via LPM should be configured as TRP. Therefore it makes sense to configure the virtual I/O server(s) as TRP. The TRP with the longest uptime is always selected as the time reference partition for the managed system. If this partition fails, the TRP with the next longer uptime is automatically chosen. Which LPARs are currently TRP on a managed system can be determined using the “lpar lsattr” command:

$ lpar -m ms01 lsattr -F name:time_ref
lpar1:0
lpar2:0
lpar3:0
lpar4:0
ms01-vio1:0
ms01-vio2:0
$

(Note: You can also omit the specification “-F name:time_ref“, the output is then simply a little longer.)

There is currently no TRP defined on the managed system ms01.

The time_ref attribute can only be set in the current configuration of an LPAR, not in a profile. Therefore, the “-d” (dynamic only) option must be used when the attribute is set using the “lpar chattr” command:

$ lpar -d chattr ms01-vio1 time_ref=1
$ lpar -d chattr ms01-vio2 time_ref=1
$

A quick check with “lpar lsattr” confirms that two time reference partitions are now configured:

$ lpar -m ms01 lsattr -F name:time_ref
lpar1:0
lpar2:0
lpar3:0
lpar4:0
ms01-vio1:1
ms01-vio2:1
$

If the time is now changed on the longest-running TRP, the time of the POWER hypervisor and service processor(s) is also updated automatically. This has no effect on the managed system’s hardware real-time clock, nor on the time of other LPARs on the managed system. Only a time delta for the POWER hypervisor and the service processors is changed. The time deltas of the LPARs on the managed systems remain unchanged.

Since newly created LPARs inherit the hypervisor’s time delta, this only has a one-time impact on newly created LPARs. After that, the time of an LPAR is independent of the time of the hypervisor.

If the time on the TRP is synchronized with NTP, the NTP time is also adopted by the POWER hypervisor and service processors.