The I/O configuration for an MVS/ESA system is kept in either of two locations, depending on which utility is used to maintain the configuration:

1. IODF data set, if you use the HCD program
2. SYS1.NUCLEUS, if you use the MVSCP program

We use HCD (MVSCP is being phased out by IBM), and have set up separate IODF data sets for each of the MVS systems that correspond to the LPAR-Mode I/O configuration in this plan for the recovery system. (See DRPMS009: Full LPAR-Mode IOCP)

When IPLing any of the MVS systems on the recovery system, you must enter a special LOAD parameter to direct the MVS operating system to its preconfigured alternate I/O configuration. For the Hitachi Data Systems GX6425 mainframe running MLPF (Multiple Logical Processor Feature), this LOAD parameter is entered on the LPRDEF screen in the PARM field for each LPAR. The CPU installation personnel will assist in setting these parameters.

The LOAD parameter consists of eight characters:

 1        2        3        4        5        6        7        8
+--------+--------+--------+--------+--------+--------+--------+--------+
| IODF DASD                         | LOADxx          |PROMPT  |ALTNUCx |
+--------+--------+--------+--------+--------+--------+--------+--------+

1. The first four characters (characters 1-4 above) specify the device number that contains the I/O defintion file (IODF) VSAM data set(s). You must specify leading zeroes for he device number If you omit this field, the system assumes that the IODF data set resides on the system residence (SYSRES) volume. To omit the field, specify all periods.

   For all of the MVS systems, omit this field by specifying four periods (e.g., "....").

2. The fifth and sixth characters specify the suffix of the LOADxx member of the SYS1.PARMLIB or SYSn.IPLPARM data set. The LOADxx member contains information on which master catalog to use, but more importantly for our purposes here, also contains an IODF statement that specifies which IODF data set to use.

   For all of the MVS systems, specify 10 (number '1', number '0').

3. The seventh character specifies the prompting/message suppression characteristics to be used during the IPL.

   You can specify one of the following values:

   P

   Do not display informational messages and prompt the operator. The system prompts the operator for both MASTER CATALOG and SYSTEM PARAMETER responses, thus overriding that information in LOADxx.

   A

   Display all messages, including informational messages, and prompt the operator. The system prompts the operator for both MASTER CATALOG and SYSTEM PARAMETER responses, thus overriding that information in LOADxx.

   M

   Display all messages, including informational messages, but do not prompt the operator for master catalog and system parameter responses. The system uses the values in LOADxx. If either or both of these values do not exist in LOADxx, the system prompts the operator for either the MASTER CATALOG or SYSTEM PARAMETER response or both.

   'blank' or 'period'

   Do not display informational messages and do not prompt the operator for master catalog and system parameter responses. The system prompts the operator only if the MASTER CATALOG or SYSTEM PARAMETER values do not exist in LOADxx.

   For all of the MVS systems, omit this field by leaving it blank.

4. The eighth character specifies the alternate nucleus identifier (0-9). Use this character at the system programmer's direction. If you do not specify an alternate nucleus identifier, the system loads the standard (or primary) nucleus (IEANUC01), unless the NUCLEUS statement is specified in the LOADxx member.

   For all of the MVS systems, omit this field by leaving it blank.

Summary

The LOAD parameter for the MVS recovery systems should all be specified as:

....10

which means to locate the SYS1.PARMLIB data set on the SYSRES volume and to use the contents of the member named LOAD10 for references to the appropriate IODF data set.

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