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IBM Power 770 and 780 (9117-MMD, 9179-MHD) Technical Overview and Introduction
4.3.2 Diagnosing
Using the extensive network of advanced and complementary error detection logic that is built
directly into hardware, firmware, and operating systems, the IBM Power Systems servers can
perform considerable self-diagnosis.
Boot time
When an IBM Power Systems server powers up, the service processor initializes the system
hardware. Boot-time diagnostic testing uses a multitier approach for system validation,
starting with managed low-level diagnostics that are supplemented with system firmware
initialization and configuration of I/O hardware, followed by OS-initiated software test routines.
Boot-time diagnostic routines include the following items:
Built-in self-tests (BISTs) for both logic components and arrays ensure the internal
integrity of components. Because the service processor assists in performing these tests,
the system is enabled to perform fault determination and isolation, whether or not the
system processors are operational. Boot-time BISTs can also find faults undetectable by
processor-based power-on self-test (POST) or diagnostics.
Wire-tests discover and precisely identify connection faults between components such as
processors, memory, or I/O hub chips.
Initialization of components such as ECC memory, typically by writing patterns of data and
allowing the server to store valid ECC data for each location, can help isolate errors.
To minimize boot time, the system determines which of the diagnostics are required to be
started to ensure correct operation, based on the way that the system was powered off, or on
the boot-time selection menu.
Run time
All Power Systems servers can monitor critical system components during run time, and they
can take corrective actions when recoverable faults occur. IBM hardware error-check
architecture provides the ability to report non-critical errors in an
out-of-band
communications
path to the service processor without affecting system performance.
A significant part of IBM runtime diagnostic capabilities originate with the service processor.
Extensive diagnostic and fault analysis routines have been developed and improved over
many generations of POWER processor-based servers, and enable quick and accurate
predefined responses to both actual and potential system problems.
The service processor correlates and processes runtime error information using logic
derived from IBM engineering expertise to count recoverable errors (called thresholding) and
predict when corrective actions must be automatically initiated by the system. These actions
can include the following items:
Requests for a part to be replaced
Dynamic invocation of built-in redundancy for automatic replacement of a failing part
Dynamic deallocation of failing components so that system availability is maintained
Device drivers
In certain cases, diagnostics are best performed by operating system-specific drivers, most
notably I/O devices that are owned directly by a logical partition. In these cases, the operating
system device driver often works in conjunction with I/O device microcode to isolate and
recover from problems. Potential problems are reported to an operating system device driver,
which logs the error. I/O devices can also include specific exercisers that can be invoked by
the diagnostic facilities for problem recreation if required by service procedures.
Summary of Contents for Power 780
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