Home > Storage > PowerMax and VMAX > Data Protection > Dell PowerMax and VMAX All Flash: SRDF/Metro Overview and Best Practices > Introduction
An SRDF createpair operation is used to add devices to an existing SRDF configuration while an SRDF movepair operation is used to move devices between existing SRDF configurations, retaining their incremental resynchronization capabilities. The HYPERMAX OS 5977.691.684 service release first introduced the ability to add new devices using a createpair command to an inactive or suspended SRDF/Metro configuration. To add new SRDF devices to an SRDF/Metro configuration in this manner, the -rdf_metro option is used with the createpair command (note –rdf_metro option has been truncated to –metro in Solutions Enabler 9.0 and beyond).
This ability was expanded with the HYPERMAX OS 5977.811.784 service release to allow the addition of net-new or unused devices to the SRDF/Metro configuration using a createpair –format command. Adding existing devices by createpair –format in this manner will erase all existing data on the specified local and remote devices.
With the PowerMaxOS 5978 release, we expanded on this base capability to allow the addition and movement of both net-new devices and those that contain existing application data to an active SRDF/Metro configuration. This will be accomplished by the addition of an –exempt option to both the createpair and movepair commands to signify that the target of the operation is an active SRDF/Metro configuration. The SRDF movepair operation, specifically, has not been supported in HYPERMAX OS releases previous to the PowerMaxOS 5978 release.
Note: For Smart DR environments, see procedures in the Smart DR subsection for Adding/Expanding Existing Devices.