NonStop NS-Series Operations Guide (H06.12+)

NOTE: The Measure utility also collects and displays statistics about system performance and
the performance of processors and other system components. Operations management personnel
often use this utility to help fine-tune and balance a system. For instructions on using this utility,
refer to the Measure User’s Guide and the Measure Reference Manual.
After the first ViewSys screen appears, press F1 to view processor busy statistics:
To exit ViewSys, press F16.
Identifying Processor Problems
Processor problems include system hangs, processor halts, OSM alarms.
Processor or System Hangs
A processor hang occurs when system components wait for an event that is not going to happen.
An unexpected event such as a deadlock (two or more processors waiting for each other) might
have occurred. In some cases, the entire system might hang, or be unresponsive.
Processor Halts
When certain errors occur (such as when data integrity is at risk), the operating system cannot
correct the problem and must halt all application and system processes running in the associated
processor. The remaining running processors in the system each send a message, reporting the
halted processor as down. The other processors in the system, including the backup to the halted
processor, are not affected by the errors that caused the processor to halt unless they are
freeze-enabled. Two types of processor halts display a processor halt code in the Processor Status
dialog box:
• A halt instruction results in a processor halt.
When the operating system detects a millicode or software error that it cannot correct, it can
execute a halt instruction to suspend all application and system processes running in the
associated processor. The status of the halted processor becomes:
Halt code = %nnnnnn
Unlike a freeze instruction, a halt instruction affects only one processor.
• A processor can be halted by a freeze instruction.
A freeze-enabled processor can be frozen by another frozen processor. When a freeze
instruction is executed, any processors that are freeze-enabled also freeze immediately.
Identifying Processor Problems 109