San Manager 5.0 - Step 3: Select synchronization settings

Select the settings that determine how data is synchronized after a communication interruption.

You can set the priority at which the controller owner of the primary volume resynchronizes data with the secondary volume after a communication interruption. You must also select the resynchronization policy, either manual or automatic.

Use the slider bar to set the synchronization priority.
The synchronization priority determines how much of the system resources are used to complete initial synchronization and the resynchronization operation after a communication interruption as compared to service I/O requests.

The priority set on this dialog applies to both the primary volume and the secondary volume. You can modify the rate on the primary volume at a later time by going to System Manager and selecting Storage > Synchronous Mirroring > More > Edit Settings.

There are five synchronization priority rates:
- Lowest
- Low
- Medium
- High
- Highest
If the synchronization priority is set to the lowest rate, I/O activity is prioritized, and the resynchronization operation takes longer. If the synchronization priority is set to the highest rate, the resynchronization operation is prioritized, but I/O activity for the storage array might be affected.
Choose whether you want to resynchronize the mirrored pairs on the remote storage array either manually or automatically.
- Manual (the recommended option) – Select this option to require synchronization to be manually resumed after communication is restored to a mirrored pair. This option provides the best opportunity for recovering data.
- Automatic – Select this option to start resynchronization automatically after communication is restored to a mirrored pair.
To manually resume synchronization, go to System Manager and select Storage > Synchronous Mirroring, highlight the mirrored pair in the table, and select Resume under More.
Click Finish to complete the synchronous mirroring sequence.

Once mirroring is activated, the system performs the following actions:

Begins initial synchronization between the local storage array and the remote storage array.
Sets the synchronization priority and resynchronization policy.
Reserves the highest-numbered port of the controller's HIC for mirror data transmission.
I/O requests received on this port are accepted only from the remote preferred controller owner of the secondary volume in the mirrored pair. (Reservations on the primary volume are allowed.)
Creates two reserved capacity volumes, one for each controller, which are used for logging write information to recover from controller resets and other temporary interruptions.
The capacity of each volume is 128 MiB. However, if the volumes are placed in a pool, 4 GiB will be reserved for each volume.

Go to System Manager and select Home > View Operations in Progress to view the progress of the synchronous mirroring operation. This operation can be lengthy and could affect system performance.