CA DRAS is a multi-tasking server. It consists of a main task, a logging task, a special processing task, and one or more normal processing tasks. The number of processing tasks is specified with the SET THREADS command in the configuration file.
In the past, if an ABEND occurred in the main task, CA DRAS came down and had to be restarted. This is still true in CA DRAS r11.6. If there is a failure of the logging or special processing tasks, CA DRAS remains running but cannot do any useful work: it will appear to "hang". A failure in a normal processing task is not fatal, and performance is degraded only if the number of remaining tasks fall below the optimum number for your workload.
Starting with CA DRAS r11, code was added to the main task to monitor the health of the subtasks. The task output will report when a processing thread is terminated. Actions taken on a reported thread failure depend on the type of subtask that is in trouble.
Although CA DRAS can continue to run without the logging task, it is not recommended. Without logging, it is impossible for you to know if work is being done or if errors are occurring. If the main task detects that the logging task has abended, the following message is written to the JES log, and a user ABEND is issued to terminate the region.
CAHFMTK023S Log task ABEND. CA DRAS is terminating.
Additionally, user ABEND U0100 is issued to force the region down.
The ABEND reason code is set to the ABEND code of the original problem. For example, if the logging task abended with a S0C4, the message is:
IEA995I SYMPTOM DUMP OUTPUT 238 ..USER COMPLETION CODE=0100 REASON CODE=400C4000
Some of the work done by CA DRAS must be serialized. A special processing subtask is started for this purpose. If it abends, CA DRAS cannot continue, and you can see the following message:
CAHFMTK025S Critical task ABEND. CA DRAS is terminating
Additionally, user ABEND U0300 is issued to force the region down.
The ABEND reason code is set to the ABEND code of the original problem. For example, if the special processing task abended with a S0C4, the message is:
IEA995I SYMPTOM DUMP OUTPUT 238 USER COMPLETION CODE=0300 REASON CODE=400C4000
When you configure CA DRAS, you specify the number of normal processing subtasks with the SET THREADS(nn) command. If one of these subtasks abends, CA DRAS alerts you with a message to SYSLOG.
For example, you specify SET THREADS(12) in your configuration file. As a result, CA DRAS attaches 12 subtasks. If one of them abends, CA DRAS issues the message:
CAHFMTK026S Processing thread ABEND. 11 of 12 threads still running
You can never see a CAHFMTK026S message that says "0 of 12 threads still running." Instead, you can see:
CAHFMTK027S All processing threads have ABENDED. CA DRAS is terminating
Additionally, user ABEND U0400 is issued to force the region down.
The ABEND reason code is set to the ABEND code of the last failing subtask. For example, if the processing task abended with a S0C4, the message is:
IEA995I SYMPTOM DUMP OUTPUT 238 USER COMPLETION CODE=0400 REASON CODE=400C4000
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