Specifying zFS file systems as sysplex-aware

This section helps you determine whether to make a zFS read/write file system be sysplex-aware.

If you are running your sysplex in a shared file system environment, where BPXPRMxx specifies SYSPLEX(YES), zFS is always enabled to allow zFS read/write sysplex-aware file systems (zFS runs sysplex=filesys). You can individually choose which file systems are sysplex-aware for read/write and which ones are not. The default is that zFS read/write file systems will not be sysplex-aware. A newly mounted zFS read/write file system will be sysplex-aware if you specify the RWSHARE MOUNT PARM, as shown:

MOUNT FILESYSTEM(’OMVS.PRV.COMPAT.AGGR001’) TYPE(ZFS) MOUNTPOINT(’/etc/mountpt’) PARM(’RWSHARE’)

As an alternative, you can specify sysplex_filesys_sharemode=rwshare in your IOEFSPRM. The default is changed so that each zFS read/write file system is mounted sysplex-aware unless you explicitly specify the NORWSHARE MOUNT PARM.

Typically, if you make a zFS read/write file system sysplex-aware, you see a performance improvement in most shared file system environments when accessing the data from a system that is not the zFS owner. However, some servers cannot fully support zFS read/write file systems that are sysplex-aware.

The z/OS® Distributed File Service SMB server cannot export any zFS read/write file systems that are sysplex-aware.
The Fast Response Cache Accelerator support of the IBM® HTTP Server for z/OS V5.3 uses an API called register file interest (BPX1IOC using the Iocc#RegFileInt subcommand). This API cannot support zFS sysplex-aware read/write file systems, so therefore the Cache Accelerator support is not able to cache static Web pages contained in files in a zFS read/write sysplex-aware file system. Other servers that use this API can also be impacted. Generally, these are servers that cache files and must be aware of file updates from other sysplex members without having the server read the file or the file modification timestamp.
The Policy Agent (Pagent) server, which is part of the z/OS Communications Server, cannot export any zFS read/write file systems that are sysplex-aware.

If you are using any of these servers, ensure that any zFS read/write file systems that are accessed by these servers are non-sysplex aware.

Note that there are some modifications to the way file system ownership works for zFS read/write sysplex-aware file systems. These modifications can cause some operational differences. For information about file system ownership, see Using zFS in a shared file system environment.