General information

Please review the following system behaviors regarding powering off:

• TC pairs are not affected when power is removed from a primary system while operations are in progress.

• When power is restored on the primary system, the system communicates with the secondary systems to confirm S-VOL pair status(es). Make sure that TC communications are fully restored (all paths have normal status) before beginning I/O operations to the P-VOL.

If the primary system accepts an I/O for a P-VOL before this, all communications are restored, and the primary system splits the pair and changes P-VOL status to PSUE-by Remote Storage System. The primary system cannot change the pair status of the S-VOL.

• If power is removed from a secondary system or from a data path component while TC operations are in progress, the primary system detects the communication failure, splits all affected pairs, and generates SIMs reporting the failures. The primary system changes the P-VOL status to PSUE-by Remote Storage System but cannot change the status of the S-VOLs.

• If a primary is powered off and the backup batteries are fully discharged while pairs are split, differential data is retained to SSD. In this unlikely case, the primary system copies differential data to the secondary system when the pairs are resynchronized.