Enabling and Disabling Capacity-on-Demand on SPARC SuperCluster

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Enabling and Disabling Capacity-on-Demand on SPARC SuperCluster

On a SPARC SuperCluster T4-4 that offers Capacity-on-Demand , a number of the cores on the compute servers can be enabled or disabled logically using the ssccod utility. Using the utility, a system can increase compute server CPU processing power when needed and then decrease it when the power is not needed. For example, a business may run 24 of the 32 cores (75%) in each SPARC SuperCluster T4-4 compute server the majority of time, and then enable the other 8 cores during the end of the quarter for running reports and queries. After the quarter-end processing is done, the 8 cores can be disabled. It is not necessary to restart the servers after running the script.

Capacity-on-Demand can be managed with the following script:

ssccod { -capacity_on_demand | -cod } { display | enable | disable }

This utility needs to be run in the control domain of each SPARC SuperCluster T4-4 compute node. To establish which nodes are your control domains, use the virtinfo shell command, which will specify "LDoms control" if you are in the control domain, e.g.:

$ /usr/sbin/virtinfo
Domain role: LDoms control I/O service root

The following table describes the parameters used with the ssccod utility.

Parameter	Description
`display`	Displays the number of CPUs in use and spare in each domain.
`enable`	Enables the spare CPUs reserved for additional on-demand capacity.
`disable`	Disables the spare CPUs.

Note - If the customer is using Solaris CPU resource controls (pools or psets) or processor binding inside any domain, these controls may need to be adjusted after Capacity-on-Demand is enabled, to allow existing workloads to utilize the newly-on-lined cores. This task is the responsibility of the customer. Similarly, the Capacity-on-Demand cores may need to be removed from resource pools or psets prior to Capacity-on-Demand being disabled. This task is also the responsibility of the customer. If existing CPU resource controls prevent Capacity-on-Demand from being disabled, the ssccod utility will inform you, and leave all spare cores enabled. This may incur additional Capacity-on-Demand operational charges. See the manual pages for pooladm(1M), poolcfg(1M), psrset(1M) and pbind(1M) for reference on Solaris CPU resource controls.