HP XP Continuous Access Software - Manual (Page 68)

Figure 30 Basic behavior in 3DC cascading configuration
If an XP Continuous Access Synchronous pair is suspended in a 3DC cascading configuration,
you can resynchronize the pair using a differential copy. If an XP Continuous Access Journal pair
is suspended, you can resynchronize the pair using a differential copy.
NOTE: To perform disaster recovery from a failure in the primary site in a 3DC cascading
configuration, ensure that the XP Continuous Access (synchronous) P-VOL's fence level is Data. If
this fence level is specified, you can perform disaster recovery using the XP Continuous Access
Journal secondary data volume containing data stored in the XP Continuous Access Synchronous
P-VOL.
If the XP Continuous Access Journal pair status is PAIR or COPY and the XP Continuous Access
Synchronous pair in a 3DC cascading configuration is recovered, the disk array automatically
splits the XP Continuous Access Journal pair.
Hardware configuration
This section explains the hardware configuration for a 3DC cascading configuration using XP
Continuous Access (synchronous) and XP Continuous Access Journal. In a 3DC cascading
configuration, three arrays are required. HP recommends that you install XP RAID Manager on
hosts in the primary, intermediate, and secondary sites. For XP Command View Advanced Edition
Software, a management station is required for these sites. The following explains hardware
configuration for these sites.
•
Local array at the primary site
XP Continuous Access Synchronous installed ◦
◦ XP Continuous Access Synchronous P-VOL
•
Local array at the Intermediate site
XP Continuous Access Synchronous installed ◦
◦ XP Continuous Access Journal installed
◦ Volume used as an XP Continuous Access (synchronous) S-VOL and an XP Continuous
Access Journal primary data volume
◦ XP Continuous Access Journal master journal volume
•
Local array at the remote site
XP Continuous Access Journal installed ◦
◦ XP Continuous Access Journal secondary data volume
◦ XP Continuous Access Journal restore journal volume
68 XP Continuous Access Journal operations requirements and restrictions