Overview of the shared file system environment

You can enable zFS to run sysplex-aware for read/write mounted file systems as well as for read-only mounted file systems. For details, see Applying required APARs for z/OS V2R1.

Beginning with z/OS® V1R13, zFS runs sysplex-aware on a file system basis (sysplex=filesys). That is, a system running zFS R13 or later in a shared file system environment is always capable of mounting zFS read/write file systems as sysplex-aware. The default is to mount all zFS read/write- file systems as non-sysplex aware. However, you can specify that you want any individual zFS read/write file system to be sysplex-aware in one of two ways:

You can specify the RWSHARE MOUNT PARM.
You can specify the sysplex_filesys_sharemode=rwshare zFS configuration option in your IOEFSPRM file. This option sets the default to be that all zFS read/write file systems are sysplex-aware, unless you specify a MOUNT PARM of NORWSHARE to make a specific file system non-sysplex aware.

Beginning with z/OS V1R13, if you specify sysplex=on in your IOEFSPRM file, zFS runs with sysplex=filesys; however, it internally sets the sysplex_filesys_sharemode value to rwshare (if you did not explicitly specify a different sysplex_filesys_sharemode value in your IOEFSPRM file). This behavior makes zFS read/write mounted file systems sysplex-aware by default. You should change your sysplex specification to sysplex=filesys, if you need to bring a V1R12 system back into the shared file system environment. You should also specify sysplex_filesys_sharemode=rwshare, if you want zFS read/write file systems to be sysplex-aware by default.

The following sections describe how the shared file system environment works using various configurations and the commands for determining the file system owner.