l1 instruction cache recoverable errors, l1 data cache correctable errors, and l2 cache correctable errors are monitored by the processor runtime diagnostics (prd) code running in the service processor. when a predefined error threshold is met, an error log with warning severity and threshold exceeded status is returned to aix. at the same time, prd marks the cpu for deconfiguration at the next boot. aix will attempt to migrate all resources associated with that processor to another processor and then stopthe defective processor.