zIIP boost

What is zIIP boost?

zIIP boost is a capability of System Recovery Boost that can improve z/OS recovery time, assuming zIIP capacity is available to the boosting image.

How does zIIP boost work?

z/OS is the only operating system that can exploit the zIIP boost capability, as it is the only OS that can natively exploit zIIPs. While zIIP boost is active, z/OS makes non-zIIP-eligible work zIIP-eligible, thus allowing most work to run on zIIPs. This provides additional capacity and parallelism to accelerate processing during the boost periods. IBM refers to this as blurring the CPs and zIIPs together.

There are variations of zIIP boost, depending on how the CPC is configured. If you have no zIIPs, you will of course see no benefit from zIIP boost. There is also the priced System Recovery Boost Upgrade feature that allows you to take additional advantage of zIIP boost.

The most basic type of zIIP boost is when you have defined Initial zIIPs and no Reserved zIIPs that could be backed by physical processors. In this case, the zIIP blurring happens for the duration of the boost, on your defined, entitled zIIPs. At the end of the boost period, normally non-zIIP eligible work stops running on zIIPs.

For the duration of the boost period, CP work is eligible to run onto any online zIIP. This additional capacity for CP work provides additional processing capacity and parallelism.