Operating System Software User Manual

1. The host sends a write request to the primary system.
2. As soon as the data is written into cache on the primary system, HP 3PAR Remote Copy
acknowledges the host write.
3. On a resynchronization schedule, HP 3PAR Remote Copy creates snapshots of all virtual
volumes within the volume group on the primary system, and the primary and backup systems
are resynchronized periodically:
• Automatically—according to the schedule specified by the setrcopygroup command
• Manually—when you issue the syncrcopy command
Figure 37 Remote Copy in Asynchronous Periodic Mode
Advantages of Asynchronous Periodic Mode
If one area of a volume is written to multiple times between two resynchronizations, remote copy
needs to send only the last write to the backup system. Therefore, asynchronous periodic mode
remote copy transfers less data overall than synchronous mode remote copy.
For more information, see “Synchronization” (page 122)
Synchronization
See the following:For more information about:
“Types of Synchronization” (page 123)The two types of synchronization that remote copy performs
“Limits on Volumes that Concurrently Synchronize”
(page 123)
The number of virtual volumes that remote copy
synchronizes at the same time
“Asynchronous Periodic Mode Volume Groups” (page 123)How remote copy synchronizes asynchronous periodic
mode volume groups
“Setting Up Resynchronization for Asynchronous Periodic
Mode” (page 126)
Considerations for resynchronizing asynchronous periodic
volume groups
“Synchronous Mode Volume Groups” (page 127)How remote copy synchronizes synchronous mode volume
groups
122 Working with Volume Groups