HP 3PAR Remote Copy Software - Manual (Page 28)

2.12 Remote Copy Configuration
Remote Copy User’s Guide InForm OS Version 2.3.1
2.5.5 Synchronous Long Distance Configuration
In Synchronous Long Distance Remote Copy configurations, a single volume group is copied
directly to volumes on two other servers by admitting the volumes to groups with two targets.
Synchronous mode Remote Copy is used between the primary server and backup server that
are physically closer to each other where a high bandwidth/low latency connection is shared,
and asynchronous periodic mode Remote Copy is used between the primary server and backup
server that are physically farther apart sharing a lesser connection (see Synchronization Types
on page 2.25 for details about synchronous and asynchronous periodic modes). The
synchronous connection must be a Fibre Channel connection while the asynchronous periodic
connections can be either all Fibre Channel (over an IP network) or all IP.
In a Synchronous Long Distance Remote Copy configuration, if one backup server fails, Remote
Copy can still continue between the primary server and the second backup server. As shown in
Figure 2-6 , when the backup server InServ2 fails, Remote Copy in asynchronous periodic mode
still continues between the primary server InServ1 and second backup server InServ3.
Conversely, if InServ3 failed, Remote Copy in synchronous mode would still continue between
InServ1 and InServ2.
NOTE: Synchronous Long Distance Remote Copy links cannot be bidirectional.