The IOTIMER command displays or specifies the time-out value in effect for disk READ and WRITE operations. Refer to the I/O Subsystem Programming Guide for an explanation of the I/O timer handling feature.

Syntax

<time-out value>

<subtype>

You can specify a <subtype> to change the IOTIMER for all packs with that subtype.

You can determine the <subtype> for a given pack from the OL PK command output, in the “SCSI/<subtype></-version> PACK” line. See the OL (Display Label and Paths) command for more information.

Explanation

Use the IOTIMER command to change the time-out value the operating system is to use for disk READ and WRITE operations. The time-out value is used to control the length of time allowed for an I/O operation. The assignment is independent of the requester of the I/O operation, such as a user application or MCP. The measurement does not represent what an application might consider to be I/O elapsed time, because there are some architectural factors that can affect the amount of time an I/O request takes, which are independent of the I/O time limit specified. If an error occurs, the time-out value is used for each retry performed by the MCP.

The unit list parameter enables you to specify a time-out value for a single disk, a range of disks, a set of disks based on a subtype (such as 53 for a SCSI/1545 pack), or all devices defined as disks in the peripheral control diagram (PCD).

The MCP default (DEFAULT) time-out value is 80 seconds. Only valid time-out values can be specified. A time-out value is preserved over a halt/load of the system, and remains in effect until the user specifies a new time-out value.

All members of a mirrored set must have the same READ and WRITE time-out value in effect. If an IOTIMER command specifies a time-out value for any member of a mirrored set, a corresponding change is automatically made to all members of the set.

IOTIMER

IOTIMER PK

IOTIMER PK ALL

Displays the I/O time-out value status of all disk units in the system.

IOTIMER PK <unit list>

Displays the I/O time-out value status of the specified disk unit or units.

IOTIMER PK <unit list> VALUE <time-out value>

Assigns the specified time-out value for all READ and WRITE operations issued to the disks identified by the unit list. If a disk is a member of a mirrored set, all disks in that set are given the specified time-out value. If the value is DEFAULT, the default value of 80 seconds is used. If the value is a valid time-out value, the specified number of seconds is used.

IOTIMER PK SUBTYPE <subtype number>

Displays the I/O time-out value status of disk units with the specified subtype number.

IOTIMER PK SUBTYPE <subtype number> VALUE <time-out value>

Assigns the specified time-out value for all READ and WRITE operations issued to the disks identified as having the specified subtype number. If a disk is a member of a mirrored set, all disks in that set are given the specified time-out value. If the value is DEFAULT, the default value of 80 seconds is used. If the value is a valid time-out value, the specified number of seconds is used.

IOTIMER PK ALL VALUE <time-out value>

Assigns the specified time-out value for all READ and WRITE operations issued to all disks defined on the system, including disks which are currently freed from the system. If the value is DEFAULT, the default value of 80 seconds is used. If the value is a valid time-out value, the specified number of seconds is used.

Examples

Example 1

This example shows the response to a simple inquiry. The display includes the unit number of the disk, the disk label, the family index, the time-out value in effect and if it was set as the MCP default, the disk description, and the disk subtype number.

IOTIMER

 -- PK ----------- TIMEOUT ----- DESCRIPTION (SUBTYPE)
   100 HLPACK #1   80 (DEFAULT)  SCSI/1545 (53)
   101 TIMERPK #2  40            SCSI/1545 (53)
   200 TIMERPK #1  40            SCSI/805 (52)2
   201 SUPPORT #2  80            SCSI/805 (52)
   300 TEST #1     20            SCSI/419 (54)
   301 TESTHOLD #1 20            SCSI/419 (54)
   302 DBPACK #1   80 (DEFAULT)  SCSI/805 (52)

Example 2

This example shows the response to

IOTIMER PK ALL VALUE DEFAULT

     IOTIMER FOR ALL PACKS SET TO MCP DEFAULT

Example 3

This example shows the response to

IOTIMER PK 201 VALUE 80

     IOTIMER FOR PK 201 SET TO 80 SECONDS

Example 4

This example shows the response to

IOTIMER PK 101 200 VALUE 40

     IOTIMER FOR PK 101 200 SET TO 40 SECONDS

Example 5

This example shows the response to

IOTIMER PK SUBTYPE 54 VALUE 20

     IOTIMER FOR PACKS OF SUBTYPE 54 SET TO 20 SECONDS