AT&T MERLIN LEGEND Installation & Maintenance Manual page 481

Maintenance and Troubleshooting
Maintenance Elements
This section describes the important elements of the
maintenance program.
Error Logs
Errors occur because of hardware malfunctions, recurring
program logic inconsistencies (PLIs), or system restarts.
Whenever an error occurs, it is entered into an error log.
Errors are classified in the error log as transient or permanent.
Basically, transient errors are intermittent and permanent errors
are steady. Each error has a threshold count that, when
exceeded, escalates an error from transient to permanent. To be
automatically cleared, each type of error must be trouble-free for
a set time period.
The error logs are
permanent system errors
transient system errors
last 10 system errors
Error logs are stored in battery-backed-up RAM.
Alarms
A permanent error causes an alarm. This alarm lights a red LED
next to a line or feature button (on a system operator console or
other designated telephone) programmed for alarm notification.
The LED stays on until the error is cleared.
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Maintenance