HP StorageWorks XP Remote Web Console Software - Manual (Page 87)

Multi-Target Configuration” (page 210) and “Changing to a 3DC Multi-Target Configuration After
Recovering from Primary Site Failures” (page 93) .
If a failure occurs in both the primary volume and the XP Continuous Access Synchronous secondary
volume, you can resume your business tasks by using the XP Continuous Access Journal secondary
data volume. After you resume the business tasks, remove the failure from the primary volume and
the XP Continuous Access Synchronous secondary volume, and transfer the business tasks back to
the primary site.
For detailed information, see “Transferring Business Tasks from an XP Continuous Access Secondary
Site to the Primary Site (in a 3DC Cascading Configuration)” (page 93) and subsequent sections.
For the delta resync configuration, the response time for host I/Os will roughly be the sum of the
above mentioned time and the creation time of journal data in the XP Continuous Access
Synchronous S-VOL.
The utilization rate of the primary site in the 3DC multi-target configuration will be higher compared
to the configuration, which consists of only XP Continuous Access Synchronous or XP Continuous
Access. Also, the utilization rate of the primary site in the 3DC multi-target configuration will be
greater than that of the configuration, which consists of only data volumes.
Hardware Configuration
A computer system in a 3DC multi-target configuration requires the following three sites:
•
Primary site for both XP Continuous Access Synchronous and XP Continuous Access Journal
•
Secondary site for XP Continuous Access Synchronous
•
Secondary site for XP Continuous Access Journal
Each of these sites requires one storage system and Remote Web Console computers. HP
recommends that RAID Manager be installed in the host computers at each of these sites.
The following list describes the hardware configuration required for storage systems at these sites:
•
Storage system at the primary site:
The storage system must have XP Continuous Access Synchronous installed. ◦
◦ The storage system must have XP Continuous Access Journal installed.
◦ The storage system must have a volume used as both an XP Continuous Access
Synchronous primary volume and an XP Continuous Access Journal primary data volume.
◦ The storage system must have an XP Continuous Access Journal master journal volume.
◦ To use the delta resync function that uses command devices, a remote command device
must be created on the XP Continuous Access Synchronous secondary site and the XP
Continuous Access Journal site. For details about creating a remote command device,
see the HP StorageWorks XP24000/XP20000 External Storage Software User Guide.
•
Storage system at the XP Continuous Access Synchronous secondary site:
The storage system must have XP Continuous Access Synchronous installed. ◦
◦ The storage system must have XP Continuous Access Journal installed.
◦ The storage system must have an XP Continuous Access Synchronous secondary volume.
This volume might be used as an XP Continuous Access Journal primary data volume
when disaster recovery is performed at the primary site. For details, see
“Recovering from
Primary Site Disaster in a 3DC Multi-Target Configuration” (page 210) .
◦ The storage system must have an XP Continuous Access Journal master journal volume.
This volume might be necessary for creating an XP Continuous Access Journal pair when
disaster recovery is performed at the primary site or when you create an XP Continuous
Interoperability with Other Products and Functions 87