Systems in non–data sharing mode have full read/write capability to the RACF® database, although they do not use the coupling facility. RACF uses hardware RESERVEs to serialize access to the RACF database (unless the installation has explicitly converted the RESERVES to global ENQs using global resource serialization). Either way, non–data sharing mode is not compatible with data sharing or read-only modes; if one system in the RACF data sharing group is in non–data sharing mode, they all are in non–data sharing mode. This mode is used when the installation wants sysplex communication enabled and does not want to use a coupling facility, but it can also be useful in certain coupling facility recovery operations.

While in non–data sharing mode, RACF ignores ENF signals, and does not automatically try to enter data sharing mode.

If the coupling facility is available and you want to enter data sharing mode, issue the RVARY DATASHARE command. If you do this when the coupling facility is not available, you enter read-only mode.