System +Health Manager Concepts

This section explains the policies involved in a process monitoring.

Relaunch policy

Once +a monitored process has failed, SHMA attempts to re-launch the process. If +all re-launch attempts fail, then SHMA either ignores the failure of the process, +or restarts the device (for a critical component).

If a monitored +component is successfully relaunched, and then subsequently fails, the next +re-launch attempt will only occur after at least KWaitTime seconds +has elapsed (since the last re-launch attempt). This mechanism is referred +to a ‘re-launch throttling’

SHMA provides a method to control process +restart which involves specifying the ‘rate of failure’ (i.e., restart) of +a monitored process. If the process's failure rate exceeds the value that +is set for the component, no new restart attempts is performed on the component. +The individual restart count decrements (if restart count is greater than +zero) at regular intervals (defined by KWaitTime patchable +constant). At a restart attempt, if the count exceeds the specified limit, +the process is not restarted and the Retry Failure policy is enacted.

Retry failure +policy

The purpose of the SHMA is to restart processes which fail +unexpectedly. Retry failure policy specifies the action to be taken by the +System Health Manager if a process fails to restart within the specified limit +(set in the patchable constant KWaitTime).

Following +are the possible courses of action:

ignore the failure
restart the OS
restart the OS in a +different start-up mode (for example, normal mode, textual mode)

Retry failure policy for each monitoring request must be specified +by the client. The client requires certain capabilities to request each course +of action.

NOTE: System Health Manager may be requested to +restart the OS when a critical process fails without attempting to restart +the failed process.

Capabilities required

When requesting monitoring, +a client requires the following capabilities:

+ + + +Retry Failure Policy +Description +Capability Required + + + + +

ESsmIgnoreOnFailure

Failure to restart is ignored, no action is taken.

None (for self monitoring)

ProtServ (for +monitoring another process)

+ + +

ESsmRestartOS

System is restarted in normal mode.

ProtServ

+ + +

ESsmRestartOSWithMode

System is restarted in a specific start-up mode based on a value +set in the ROM.

ProtServ and PowerMgmt

+ + +

ESsmCriticalNoRetries

System is restarted (with no attempts to restart the component being +attempted).

ProtServ

+ + + +