Browse Prior Art Database

Dynamic Single Point of Failure Detection of An I/O System Disclosure Number: IPCOM000033032D
Original Publication Date: 2004-Nov-22
Included in the Prior Art Database: 2004-Nov-22
Document File: 2 page(s) / 56K

Publishing Venue



Provides a monitoring mechanism to give the customer a warning when a single point of failure threatens the system, by scanning the original I/O configuration to form a base delta and merging secondary deltas formed by dynamic I/O changes and verifying on a internal I/O mapping.

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Dynamic Single Point of Failure Detection of An I /O System

SPFD verifies that the original I/O definition of hardware is single point of failure free at initial program load time. This scan provides a base delta to compare future I/O changes against, however single points of failure can exist in the original I/O definition without the customer knowing about it. Secondary delta's come from I/O configuration changes and are merged in at change time to form the current virtual definition.

    At change time the virtual definition gets checks for the following causes of a single point of failure. - A DASD/Tape (Or simply not Console/CTC) that only has one path.

- A single Console/CTC on that definition. (There should exists more than one Console/CTC on a system.) - A device that has more than one path that goes through the same control unit.

Here is a visual example on how this idea works.

I/O Change

I/O changes merged


Current I/O Delta Data structure

Current I/O Delta Data structure


DACH Delta

DACH Delta

1. Chpid A0 gets pulled out.
2. I/O change gets presented to ENF33 Listeners.
3. DACH Delta gets merged into Base I/O delta and other secondary deltas.


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1. The Delta removes the A0 chpid
2. This causes a Single Point of Failure on the B0 chpid.
3. The following warning is outputed.

W A R N IN G : S P F D E T E C T E D O N D E V IC E 9 8 0 , D U E T O

C H P ID A 0 B E IN G C O N F I...