PJ45739 – System recovery boost support
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System recovery boost is z/TPF support of Instant Recovery that is available on the IBM z15 (z15) system. System recovery boost provides more processing power to allow the z/TPF system to recover from an outage and to process pent-up demand following an outage.
The z/TPF system supports two types of boost. First, speed boost increases a subcapacity processor to run at full capacity for a period of time following an outage. Speed boost is turned on during IPL, and it remains active for as long as 15 minutes after the z/TPF system reaches NORM state. For example, when the z/TPF system is running in an LPAR on an IBM z15 8561-610 processor, speed boost increases the z/TPF LPAR so that it runs as an 8561-710 processor. After z/TPF is in NORM state for 15 minutes following the outage, the z/TPF LPAR returns to run as an 8561-610 processor.
Second, I-stream boost uses all fenced I-streams for a period of time following an outage. I-stream boost is turned on during an IPL and remains active for as long as 20 minutes after the z/TPF system reaches NORM state. I-stream boost is turned off by collapsing one I-stream every minute until the I-stream cap is reached. For example, if the z/TPF LPAR has 15 I-streams and the I-stream cap is set to 10, the z/TPF system uses all 15 I-streams following an outage. After z/TPF is in NORM state for 20 minutes, IS-15 is collapsed. 21 minutes after the z/TPF system reaches NORM state, IS-14 is collapsed. 22 minutes after the z/TPF system reaches NORM state, IS-13 is collapsed and so on until all I-streams above IS-10 are collapsed.
Speed boost and I-stream boost must be enabled by using the ZBOST command before either is turned on during an IPL.
Also, speed boost and I-stream boost are available only on a z15 or later.
For more information, see APAR PJ45739.