TrueCopy operations take place between a primary storage system and a secondary storage system. The primary storage system communicates with the secondary storage system over dedicated Fibre Channel or iSCSI data paths called remote copy connections.
- Managing host I/O operations to the P-VOL.
- Managing initial copy and update copy operations between the P-VOL and the S-VOL.
- Managing pair status and configuration information.
The MCU is the control unit in the primary storage system that controls the P-VOLs of the TrueCopy pairs. The MCU communicates with the RCU through the dedicated remote copy connections. The MCU controls the host I/O operations to the P-VOLs as well as the TrueCopy remote copy operations between the P-VOLs and S-VOLs. The MCU also manages the TrueCopy pair status and configuration information.
The secondary storage system is responsible for the following:
- Managing copy operations issued by the primary storage system to the S-VOL.
- Assisting in the management of pair status and configuration (for example, rejecting write I/Os to the S-VOL).
The RCU is the control unit in the secondary storage system that controls the S-VOLs of the TrueCopy pairs. The RCU assists in managing the TrueCopy pair status and configuration (for example, rejects write I/Os to S-VOLs). The RCU executes the remote copy operations issued by the MCU. The RCUs should be attached to a host system to allow sense information to be reported in case of a problem with a secondary volume or remote storage system and to provide disaster recovery capabilities.
If the primary storage system is VSP One Block, the secondary system can be VSP E series, or VSP G/F350, G/F370, G/F700, G/F900.