SSI Statement

Purpose

Use the SSI statement to define the name of the single system image (SSI) cluster and the systems that are members of the SSI cluster. The statement also identifies the location of the persistent data record (PDR).

How to Specify

SSI is an optional statement. If specified, only one statement is allowed. Subsequent SSI statements cause a message to be displayed and are ignored. Each slot can be specified only once. The SSI statement must be the same for all members in the SSI cluster.

The system initializing with a system configuration file containing the SSI statement must be one of the members of the SSI cluster. The SSI statement must be processed after the system name has been established by a previous SYSTEM_IDENTIFIER or SYSTEM_IDENTIFIER_DEFAULT statement.

Operands

ssi_name

is the name of the SSI cluster. The name can be up to eight alphanumeric characters.

PDR_VOLume volid

tells CP the volume label of the device that contains the persistent data record (PDR) for the SSI cluster. If omitted, the default is the volume containing the active PARM disk. The volume must be included in either the CP-owned or user volume list.

PDR_VOLume &SYSPARM

tells CP that the volume containing the active PARM disk is the device that contains the persistent data record (PDR) for the SSI cluster.

SLOT n

tells CP the number of the slot in the SSI member list. n must be a decimal number from 1 to 4. If any of the slots is not specified, it will automatically be defined as AVAILABLE.

sysname

AVAILABLE

is the 1- to 8-character system name of a system that is a member of the SSI cluster. The system name must be alphanumeric.

AVAILABLE tells CP the slot is available for future use.

All members in an SSI cluster must be part of the ISFC collection that contains the SSI cluster. All members in the SSI cluster participate in all SSI-defined functions and services.

Usage Notes

1. Before the first system can join the SSI cluster, you must format the cylinders containing the persistent data record (PDR). You can do this by using the FORMSSI utility. For more information, see FORMSSI.
2. The PDR volume must be an ECKD device and either a CP-owned DASD or in the user volume list.
3. When an SSI statement is specified, ACTIVATE ISLINK statements must also be specified to define direct ISFC connections to each of the other members of the SSI cluster. If other member(s) are joined to the cluster during IPL of an SSI member, ISFC connections to the joined members must be established before the system operator is logged on and IPL completes.
   • If there is not an ISFC connection to every joined member, message HCP1669I is displayed and the system waits until there are connections to all joined members.
   • If there are not enough ACTIVATE ISLINK statements to define direct connections to every joined member, message HCP1670E is displayed, followed by disabled wait state 1670.
4. If an error related to an SSI statement is found, a wait state 1682 occurs. Allowing the system to continue initialization as if it were not a member of an SSI cluster could result in loss of data. The wait state enables you to fix the problem without risking the loss of data.
5. If an SSI statement is found in the system configuration file, the system is defined as a member of an SSI cluster. Because of this membership, any system configuration file statements that define non-SSI cross-system linking are not allowed and result in a disabled wait state during IPL. The following is a list of configuration statements that conflict with an SSI statement:
   • XLINK_DEVICE_DEFAULTS
   • XLINK_SYSTEM_EXCLUDE
   • XLINK_SYSTEM_INCLUDE
   • XLINK_VOLUME_EXCLUDE
   • XLINK_VOLUME_INCLUDE
6. If you want to add a new system to the SSI cluster, add the new system in an available slot in the SSI member list by using the CP SET SSI command and then promptly update the SSI statement. For more information, see SET SSI.
7. If you change the order of the members in the SSI member list, a cold start is required on all systems in the SSI cluster. A cold start deletes spool files. Files that are to be preserved during such a change should be dumped to tape using the CP SPXTAPE DUMP command. After the cold start, use SPXTAPE LOAD to restore the spool files.
8. The SET SSI PDRVOLUME command can be used to replace the current PDR volume with a new PDR volume. After each successful SET SSI PDRVOLUME command, always update the SSI configuration statement with the new PDR volume and make sure that the new PDR volume appears in either the CP-owned or user volume list in the system configuration file.