Use this command to specify how often the DASD queues are scanned by the
CYED program for I/O requests that are not being processed by the TPF system
in a timely method.
Requirements and Restrictions
None.
Format
- Time-seconds
- indicates the time interval for scanning the module queues, where
seconds is the number of seconds from 0-999.
- Note:
- The time interval is initially set to 0 by the TPF system.
Additional Information
- When running on a VM system, the specified scan interval is
doubled.
- If the value for the ZSONS ALTER HALT command is not set to 0, the CYED
program takes the normal DMIH timeout value (5 seconds), doubles that value
and adds the halt value to the result. If scan indicates that the queue
is stalled for at least that long, the CYED program starts the DMIH recovery
routine, which issues a CTL-003A dump, resets the device, and redrives the
first request on the module queue.
- The CYED program scans every DASD module queue for outstanding
requests. When a queue with an outstanding request is found, the top
request on that queue is flagged. When the next scan is performed, the
module queue is checked to see if the indicator is still set. If it is,
this indicates that the DASD support did not process the request in the
specified time period. Therefore, the requests for this module are not
proceeding at a reasonable rate. When this occurs, the CYED program
sends an attention message and takes no additional recovery action. In
summary, if a module queue is actually stalled (or is not completing), the
CYED program sends an attention message at each scan interval until the queue
does proceed.
- Although the time interval is initially set to 0 by the TPF system, the
module queues are actually scanned every 5 seconds by default.
- Enter the ZSONS DISPLAY SCAN command to display the current time interval
for scanning the module queues.
Examples
In the following example, the time value used to schedule the next module
queue scan is set to 15 seconds.
+--------------------------------------------------------------------------------+
|User: ZSONS A S T-15 |
| |
|System: SONS0002I 09.40.59 SCAN TIME VALUE IS 15 |
+--------------------------------------------------------------------------------+
Related Information
See TPF Database Reference for more information
about DASD support.