Scenario 1: First system in the sysplex

Figure 1 and Figure 2 show a z/OS UNIX file system configuration for a shared file system. SYSPLEX(YES) and a value on VERSION are specified, and a directory is dynamically created on which the version file system data set is mounted. This type of configuration requires a sysplex root and system-specific file system.

Guideline: After you create the directories for each system-specific file system and the version root file system, use the TSO UNMOUNT command to remount the sysplex root as read-only. Remounting the sysplex root file system as read-only prevents accidental corruption or full-file system problems with the sysplex root, both of which might require a sysplex IPL to recover. Additionally, most configurations will show improved performance if the file system is mounted as read-only. If a new directory needs to be added to the sysplex root file system, you can do the following tasks without disrupting the availability of the file system:

Use the TSO UNMOUNT command to remount the read-only file system to read/write mode.
Create the new directories.
Remount the file system in read-only mode.

Figure 1. BPXPRMxx setup — sharing file systems

BPXPRMxx for (SY1)

FILESYSTYPE
TYPE(ZFS)
ENTRYPOINT(IOEFSCM)
ASNAME(ZFS)

VERSION('REL9')
SYSPLEX(YES)

ROOT
FILESYSTEM ('OMVS.SYSPLEX.ROOT')                 1 
TYPE(ZFS) MODE(READ)

MOUNT
FILESYSTEM('OMVS.&SYSNAME..SYSTEM.ZFS')          2 
TYPE(ZFS) MODE(RDWR) UNMOUNT PARM('NORWSHARE')  
MOUNTPOINT('/&SYSNAME')

MOUNT
FILESYSTEM('OMVS.ROOT.ZFS')                      3 
TYPE(ZFS) MODE(READ)
MOUNTPOINT('/$VERSION')

MOUNT
FILESYSTEM('OMVS.&SYSNAME..DEV')                 4 
TYPE(ZFS) MODE(RDWR) UNMOUNT PARM('NORWSHARE') 
MOUNTPOINT('/&SYSNAME/dev')

MOUNT
FILESYSTEM('OMVS.&SYSNAME..TMP')                 5 
TYPE(ZFS) MODE(RDWR) UNMOUNT PARM('NORWSHARE') 
MOUNTPOINT('/&SYSNAME/tmp')
.
.
.

1 This is the sysplex root file system and was created by running the BPXISYZR job. To create a sysplex root file system that is a HFS, run the sample job BPXISYSR. Because AUTOMOVE is the default, another system can take ownership of this file system when the owning system goes down.
2 This is the system-specific file system, and was created by running the BPXISYZS job. To create a system-specific file system that is a zFS, run the sample job BPXISYSS. It must be mounted read/write. UNMOUNT is specified because this file system is system-specific and ownership of the file system should not move to another system if the owning system go down. The MOUNTPOINT statement /&SYSNAME. will resolve to /SY1 during parmlib processing. This mount point is created dynamically at system initialization.
3 This is the previous root file system (version file system).
Guideline: It should be mounted read-only. Its mount point is created dynamically and the name of the file system is the value specified on the VERSION statement in the BPXPRMxx member. AUTOMOVE is the default and therefore is not specified, allowing another system to take ownership of this file system when the owning system goes down.
4 This file system contains the system-specific /dev information. UNMOUNT is specified because this file system is system-specific; ownership should not move to another system should the owning system go down. The MOUNTPOINT statement /&SYSNAME./dev will resolve to /SY1/dev during parmlib processing.
5 This file system contains system-specific /tmp information. UNMOUNT is specified because this file system is system-specific; ownership should not move to another system if the owning system goes down. The MOUNTPOINT statement /&SYSNAME./tmp will resolve to /SY1/tmp during parmlib processing.

Figure 2. Shared file systems in a sysplex What a shared file system in a sysplex looks like

If the content of the symbolic link begins with $VERSION or $SYSNAME, the symbolic link will resolve in the following manner:

If you specify SYSPLEX(YES) and the symbolic link for /dev has the contents $SYSNAME/dev, the symbolic link resolves to /SY1/dev on system SY1 and /SY2/dev on system SY2.
If you specify SYSPLEX(YES) and the content of the symbolic link begins with $VERSION, $VERSION resolves to the value nnnn specified on the VERSION parameter. Thus, if VERSION in parmlib is set to REL9, then $VERSION resolves to /REL9. For example, a symbolic link for /bin, which has the contents $VERSION/bin, resolves to /REL9/bin on a system whose $VERSION value is set to REL9.

In the previous scenario, if ls –l /bin/ is issued, the user expects to see the contents of /bin. However, because /bin is a symbolic link pointing to $VERSION/bin, the symbolic link must be resolved first. $VERSION resolves to /REL9 which makes the path name /REL9/bin. The contents of /REL9/bin will now be displayed.