HP 3PAR Operating System Software - Manual (Page 21)

SLD configurations differ from 1-to-N configurations as follows:
•
In SLD configurations, remote-copy volumes on the primary system are in a remote-copy
relationship with two secondary volume groups. Virtual volumes in the primary system are
included in two primary groups, one copied to a backup system in synchronous mode, and
one copied to the other backup system in asynchronous periodic mode. The two primary
groups can be started and stopped independently of each other.
•
For the SLD volume groups, one remote-copy pair must be configured in synchronous mode
and the other in asynchronous periodic mode.
•
The SLD volume groups on the two backup systems are configured with a standby link for
additional failover and recovery options.
Follow these steps to set up SLD remote copy:
1. Remote copy is set up in synchronous mode between the primary system and one backup
system. For more information, see
“Synchronous Mode” (page 120) .
With HP 3PAR OSs earlier than 3.1.2, the synchronous connection must be a Fibre Channel
(FC) connection. With HP 3PAR OS 3.1.2 or later, RCFC and RCIP connections are supported.
For more information, see
“Fibre Channel Networks” (page 24) and “SLD Remote-Copy
Considerations” (page 56) .
2. Remote copy is set up in asynchronous periodic mode between the primary system and backup
system that are physically farthest apart (and therefore share a lesser connection). For more
information, see
“Asynchronous Periodic Mode” (page 121) .
The asynchronous periodic connection can be either all IP connections or, if all the SLD systems
are four-node storage systems, all FC over IP network connections. For more information, see
“Fibre Channel over IP Networks” (page 24) and “IP Networks” (page 23) .
NOTE: SLD remote-copy links can be bidirectional between two HP 3PAR StoreServ Storage
systems that are in synchronous relationship with each other. This enables customers to configure
two SLD configurations among three HP 3PAR StoreServ Storage systems.
Figure 6 (page 21) illustrates an SLD remote-copy configuration.
Figure 6 SLD Remote Copy
Synchronous Long Distance Configuration 21