Statements/parameters for MIH

Note: IBM® suggests you not set a MIH time value for any device that establishes its own primary or secondary time interval. Overriding the device-supplied primary MIH timeout value might adversely affect MIH recovery processing for the device or device class. Refer to the specific device's reference manuals to determine if the device supports self-describing MIH time values. See the topic Missing interrupt handler (MIH) for more information.

CHAR=mm:ss

Specifies the MIH time interval to be used for the character reader device class, where mm is minutes and ss is seconds.

Value Range:

mm = 00-99
ss = 00-59

Default: 03:00

COMM=mm:ss

Specifies the MIH time interval to be used for the communications device class, where mm is minutes and ss is seconds.

Value Range:

mm= 00-99
ss = 00-59

Default: 03:00

CTC=mm:ss

Specifies the MIH time interval to be used for the channel-to-channel device class, where mm is minutes and ss is seconds.

Value Range:

mm = 00-99
ss = 00-59

Default: 03:00

DASD=mm:ss

Specifies the MIH time interval to be used for all direct access devices (DASD), where mm is minutes and ss is seconds.

Value Range:

mm = 00-99
ss = 00-59

In general, the default time interval (15 seconds) is sufficient for most DASD configurations. However, IBM suggests you not specify any MIH for DASD if you have any DASD hardware in your configuration that uses the primary or secondary MIH timing enhancement. See the topic Missing interrupt handler (MIH) for more information.

Default: 00:15

IOTDASD=mm:ss

Specifies the I/O timing limit to be used for all non-paging direct access storage devices (DASD), where mm is minutes and ss is seconds. The maximum I/O timing limit is 5,999 seconds. When IOTDASD is set to 00:00, I/O timing is not in effect for the DASD device class.

Value Range:

mm = 00-99
ss = 00-59

Note that initially, the time interval is set to 00:00, which indicated that the I/O timing facility is not active for any DASD.

Note also that the MSGONLY keyword can also be used to set I/O timing message-only processing on or off for all DASD devices.

Default: 00:00

DEV=devnum

Specifies the device number(s) for the device(s) for which specific time intervals are to be used. To specify more than one device number, use a comma to separate the device numbers. To specify a range of device numbers, use a hyphen to separate the beginning and ending device numbers. If more than one device number is specified, enclose the device numbers in parentheses.

Note: The DEV keyword must precede or follow the TIME keyword on the same record.

Value Range: 1 to 4 hexadecimal digits, optionally preceded by a slash (/).

Default: None

GRAF=mm:ss

Specifies the MIH time interval to be used for the graphics device class, where mm is minutes and ss is seconds.

Value Range:

mm = 00-99
ss= 00-59

Default: 03:00

HALT=mm:ss

Specifies the MIH time interval to be used for monitoring Halt (HSCH) and clear (CSCH) subchannel operations. This keyword is device independent; setting it affects all devices on the system.

Value Range:

mm = 00-99
ss= 00-59

Default: 00:05

IOTHSWAP=YES|NO

Specifies whether the I/O timing facility is enabled for HyperSwap®.

Default: NO. The I/O timing facility is not enabled to trigger a HyperSwap.

IOTTERM=YES|NO

Valid only when IOTHSWAP=YES. Specifies whether a timed out I/O operation that triggers a HyperSwap is terminated with a permanent error or allowed to be started on the swap 'TO' device.

Default: NO. The timed out I/O operation is allowed to be started on the swap 'TO' device.

MSGONLY=YES|NO

Specifies whether an I/O timeout condition is processed using full I/O timing recovery (MSGONLY=NO) or message only recovery (MSGONLY=YES). When MSGONLY=NO is specified and an I/O request exceeds the I/O timing interval, a message is issued to the operator, a record is written to SYS1.LOGREC, and the I/O request is abnormally terminated. When MSGONLY=YES is specified and an I/O request exceeds the I/O timing interval, a message is issued to the operator and a record is written to SYS1.LOGREC, however, the I/O request is NOT abnormally terminated. Instead, the request is left in the system.

Message-only processing allows the system to detect I/O timeout conditions, but, provides the ability to allow the user to decide which I/O requests should be terminated.

Note:

If more than one MSGONLY keyword appears on a record, the last valid MSGONLY keyword is used.
The MSGONLY keyword is only valid when the IOTDASD keyword is specified or when the DEV and IOTIMING keywords are specified. Otherwise, the MSGONLY keyword is ignored. This implies that the MSGONLY keyword value only relates to devices that are affected by the IOTDASD or DEV/IOTIMING keywords.

Default: NO

MNTS=mm:ss

Specifies the MIH time interval to be used for monitoring ‘mount pending’ conditions for DASD and TAPE devices.

Value Range:

mm = 00-99
ss= 00-59

Default: 03:00

MOUNTMSG=YES|NO

Specifies that MIH is to issue all MIH mount pending messages.

Default: NO

STND=mm:ss

Specifies the MIH time interval to be used for all of the following device classes:

Character readers (CHAR)
Communications (COMM)
CTCs (CTC)
Graphics (GRAF)
Tapes (TAPE)
Unit records (UREC).

Specify the time interval as mm:ss, where mm is minutes and ss is seconds.

If you code STND following CHAR, COMM, CTC, GRAF, TAPE, or UREC, the value for STND overrides the values for those device classes. Similarly, if you code CHAR, COMM, CTC, GRAF, TAPE, or UREC following STND, the values for those device classes override the value for STND.

In this example, the value for the CTC device class is 4:00, because the value specified for STND overrides the value specified for CTC. However, the value for the tape device class is 5:00, because the value specified for TAPE overrides the value specified for STND. Thus, this MIH record sets the values for CHAR, COMM, CTC, GRAF, and UREC to 4:00, and sets the value for TAPE to 5:00.

SETIOS MIH,CTC=01:00,STND=04:00,DASD=00:10,HALT=00:08,TAPE=05:00

Value Range:

mm = 00-99
ss= 00-59

Default: 03:00

TAPE=mm:ss

Specifies the MIH time interval to be used for the tape device class, where mm is minutes and ss is seconds.

Value Range:

mm = 00-99
ss= 00-59

IBM suggests the following time intervals, based on tape device class:

Tape Device Class	Time Interval
3480	5 minutes
3490	5 minutes
3490E	10 minutes
3490E (When loaded with IBM Enhanced Capacity Cartridge System Tape)	20 minutes

Note: You may specify either TAPE (such as ‘TAPE=10:00’), or a combination of DEV and TIME, for example:

         DEV=(4A1-4E7),TIME=10:00

The time interval you set with the TAPE parameter will apply to all tape device types. You cannot set time intervals for specific esoteric or generic groups.

IBM suggests you not specify any MIH for the tape device class if you have any tape device in your configuration that uses the primary or secondary MIH timing enhancement. See the topic Missing interrupt handler (MIH) for more information.

Default: 03:00

TEST

Specifies the system is to dynamically test MIH parameters and values. The TEST parameter is ignored during initialization. The system uses this parameter when you issue a SET IOS=xx command to syntax check the MIH updating.

TIME=mm:ss

Specifies the MIH time interval to be used for the devices identified on the DEV keyword, where mm is minutes and ss is seconds.

Note: The TIME keyword must precede or follow the DEV keyword on the same record.

Value Range:

mm = 00-99
ss= 00-59

Default: None

UREC=mm:ss

Specifies the MIH time interval to be used for the unit record device class, where mm is minutes and ss is seconds.

Value Range:

mm = 00-99
ss= 00-59

Default: 03:00

Syntax considerations for MIH:

On MIH records, specify the DEV and TIME keywords as a pair. That is, use them together on one record to define time intervals for specific device numbers.
On MIH records, only one pair of DEV and TIME keywords can appear on any one record. They can appear in any order, and can be separated by other keywords.
On MIH records, if the same device number exists in more than one DEV keyword, the time interval specified for the last occurrence of the DEV keyword (containing the device number) will be used.
You can code an MIH time interval and I/O timing limit on the same record when either of the following is true:
- All the devices listed in the record are to be monitored by both the MIH and the I/O timing facility. In the following example, device A20 and devices A11, A12, and A14 will have both an MIH time interval of 5 seconds and an I/O timing limit of 11 seconds:
```
MIH DEV=(A20,A11-A14),TIME=00:05,IOTIMING=00:11
```
- A device class is to be monitored by the MIH, and an individual device (or range of devices) is to be monitored by the I/O timing facility.
  When the device class is DASD, the MIH will monitor all DASD devices, including those specified on the DEV parameter. The I/O timing facility will monitor only those devices specified on the DEV parameter. In the following example, the DASD device class will have an MIH time interval of 5 seconds. Device A20 and devices A11, A12, A13, and A14 will have an MIH time interval of 5 seconds, and will also have an I/O timing limit of 11 seconds.
```
MIH DASD=00:05,DEV=(A20,A11-A14),IOTIMING=00:11
```
  When the device class is not DASD, the MIH will monitor the device class, and the I/O timing facility will monitor only those devices specified on the DEV parameter. In the following example, the tape device class will have an MIH time interval of 5 minutes. Device B12 is a DASD device, because only DASD devices can be monitored by the I/O timing facility. Device B12 will have an I/O timing limit of 10 seconds.
```
MIH TAPE=05:00,DEV=B12,IOTIMING=00:10
```
To request that the MIH monitor one device (or range of devices) and the I/O timing facility monitor device (or range of devices), code two separate records.
You can establish I/O timing for the entire DASD device class by using a device class name of IOTDASD. In the example below, an I/O timing limit of 1 minute is established for all DASD devices.
```
MIH IOTDASD=01:00
```
- When the IOTDASD device class name is specified with the DEV and IOTIMING keywords, all devices specified on the DEV keyword will have an I/O timing limit equal to the limit specified on the IOTIMING keyword. In the example below, an I/O timing limit of 5 seconds is established for DASD devices 180 through 18F and an I/O timing limit of 30 seconds is established for all other DASD devices.
```
MIH IOTDASD=00:30,DEV=(180-18F),IOTIMING=00:05
```
- To request that the I/O timing facility monitor a device (or devices) with message-only processing active, use the MSGONLY keyword. In the following example, an I/O timing limit of 1 minute is established for all DASD devices. Furthermore, message-only processing is established for all DASD devices. This implies that if any I/O request to any DASD device exceeds the I/O timing limit, then the system will issue a message, record the condition in SYS1.LOGREC, and will NOT abnormally terminate the I/O request. Instead, the request is left in the system. If another I/O timing interval expires, the system will reissue a message, and rerecord the condition in SYS1.LOGREC.
```
MIH IOTDASD=01:00,MSGONLY=YES
```
  In the following example, an I/O timing limit of 10 minutes and message-only processing is established for device 180 through 18F.
```
MIH DEV=(180-18F),IOTIMING=10:00,MSGONLY=YES
```
  To turn off message-only processing, either use the MSGONLY=NO keyword, or set the I/O timing limit for the device (or devices) to zero (00:00).
  
  Note: Indicating IOTDASD=00:00 will not turn off I/O timing nor reset message-only processing for any devices that were explicitly set up for I/O timing using the DEV and IOTIMING keywords.
You can code I/O Timing HyperSwap options to specify if the I/O timing facility is allowed to trigger a HyperSwap and if so, whether to terminate the I/O operation that is timed out or allow it to be started on the swap 'TO' device.
The following conditions must be true before an I/O timeout will trigger a HyperSwap:
- The I/O timing facility must be enabled for HyperSwap.
- The product must be installed at a level that supports the I/O timing trigger.
- Message-only recovery is not in effect for the device on which the timeout occurred and the timeout is not the result of timing specified by the I/O driver program.
The following example specifies that the I/O timing facility is enabled for HyperSwap and that timed-out I/O operations are allowed to be started on the swap 'TO' device:
```
MIH,IOTHSWAP=YES,IOTTERM=NO
```
On MIH records, specify the IOTHSWAP and IOTTERM keywords as a pair. That is, use them together on one record to define the actions to be taken for an I/O Timing HyperSwap trigger.