When you create a copy pair, the contents of the P-VOL are copied to the S-VOL track by track (not including diagnostic and unassigned alternate tracks). The initial copy operation synchronizes the P-VOL and S-VOL independently of host I/O processes.
If you know that the data in the P-VOL and S-VOL are already identical, or if the P-VOL does not yet contain any data, you can select the None initial copy option. When you select this option, the pair becomes synchronized (PAIR status) immediately. You can also specify the following options to control the impact of the initial copy operations on the storage system performance:
- Copy Pace. Specifies the number of tracks that are copied simultaneously
before the P-VOL accepts another host I/O request. If more tracks are copied, the
initial copy operation is completed more quickly. If fewer tracks are copied,
storage system performance (for example, host I/O response time) is maintained at a
higher level. You can set this option when you create pairs. The following table
lists the values for the copy pace and the transfer size per remote I/O (RIO).
Copy pace Transfer size OPEN-V 1 256 KB (256 KB x 1) 2 512 KB (256 KB x 2) 3 768 KB (256 KB x 3) 4 1024 KB (256 KB x 4) - Maximum Initial Copy Activities. Specifies the maximum number of concurrent initial copy operations.
When using CCI, you can specify the maximum number of initial copies by using the raidcom modify remote_replica_opt -copy_activity command.
- Initial Copy Priority. Initial copy operations are performed in the order specified for LUs and LDEVs in the configuration definition file.
- Round Trip Time. You can specify the time limit for data to travel from the P-VOL to the S-VOL. This value is used by the storage system to control initial copy pace when update copying is in progress. When you use CCI, you can specify the value using the raidcom modify rcu command.