How to Enable Deadman Kernel Code in Solaris 8 and Newer to Force a Kernel Panic During a Hang (Doc ID 1004530.1)

Goal

The Solaris Operating System contains a deadman timer.  The code in the OS checks to see if the 'clock' thread is not able to run, which can be one of the causes of a system hang.  If the deadman timer is enabled, and the clock cannot run, the system will panic and produce a crash dump for a kernel engineer to analyze, to try and determine the cause of the hang.  A support engineer may recommend that this feature be enabled when other methods of forcing a panic are unsuccessful, in order to collect data needed to solve a system hang issue.  Once the problem is solved, this feature should be disabled again.

Analysis of the resulting crash dump can give information on the cause of the hang. The deadman timer is implemented in different ways on different hardware platforms and different OS releases. Some combinations of platform and OS allow you to configure the time between a hang occurring and a panic being forced.

This document explains how to enable the deadman timer and how to configure the time taken until the deadman code forces a panic. It also gives pointers to how to collect information which can be used to analyze why the system hung.

Solution