Home > Storage > PowerMax and VMAX > Data Protection > Dell PowerMax and VMAX All Flash: SRDF/Metro Overview and Best Practices > Device pair synchronization
Once the devices in the SRDF group are made read/write (RW) on the SRDF link, invalid tracks begin synchronizing between the R1 and R2 devices, with the direction of synchronization defined by an establish or restore operation. The SRDF mode will remain Active with the device pair state becoming SyncInProg while the device pairs are synchronizing. During synchronization, the R1 side will remain accessible to the host while the R2 side remains inaccessible to the host.
An SRDF device pair will exit the SyncInProg SRDF pair state when either of the following occurs: