Browse Prior Art Database

A Method for Eliminating the False Detection of Hot I/O

IP.com Disclosure Number: IPCOM000110459D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 52K

Publishing Venue

IBM

Related People

Meritt, AS: AUTHOR [+2]

Abstract

A method for eliminating the false detection of Hot I/O conditions is disclosed. The method reduces unnecessary system disruption caused by recovery actions from false hot I/O.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 81% of the total text.

A Method for Eliminating the False Detection of Hot I/O

      A method for eliminating the false detection of Hot I/O
conditions is disclosed.  The method reduces unnecessary system
disruption caused by recovery actions from false hot I/O.

      Hot I/O is defined as a condition where an Input/Output device
or control unit failure causes a multitude of unsolicited interrupts
to be presented to the host computer without any successful attempts
to perform an I/O operation.  This condition causes the consumption
of system resources and prevents useful work from being done.

      A common method to overcome this condition is to invoke special
recovery routines when a certain threshold of interrupts is exceeded.
However, it is possible that normal conditions can cause the
operating system to exceed the hot I/O threshold and invoke both the
initial default hot I/O recovery and the installation specified
recovery, causing system disruption.

      In order to eliminate false hot I/O conditions from causing
recovery actions, the following enhancement has been made to the hot
I/O detection algorithm:

      If the hot I/O count for the device is within a certain number,
say, 5, of the system hot I/O threshold, then
      o    Invoke asynchronous I/O processing to force an I/O
operation to the device
      o    When the asynchronous I/O processor gets control it
attempts a sense operation to the device.  If the sense operation
completes with p...