Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

(secondary volume). To identify HP-UX device files corresponding to each device represented
by CU:LDEV execute the following command:
#ls /dev/rdsk/* | raidscan -find –fx
NOTE: Only OPEN-V LUNs are supported in a Three Data Center configuration. The ioscan
output must be checked to verify which LUNs are OPEN-V LUNs.
9. Determine which devices will be used by the application package.
10. Define a device group that contains all of these devices. For normal Three Data Center
operations, a package requires three different device groups for the configuration.
For Tri-Link configurations, a package requires three different device groups: Continuous
Access Synchronous or Continuous Access journal device group between DC1
and DC2, Continuous Access journal device group between DC1 or DC2 and DC3,
and a Delta Resync device group from either DC1 or DC2 to DC3 depending on where
Continuous Access journal pair to DC3 is configured.
For Multi-Target Bi-Link configuration, a package requires three different device groups:
Continuous Access Synchronous or Continuous Access journal device group
between DC1 and DC2, Continuous Access journal device group between DC1 and
DC3, and a phantom device group between DC2 and DC3.
For Multi-Hop Bi-Link configuration, a package requires three different device groups:
Continuous Access Synchronous or Continuous Access journal device group
between DC1 and DC2, Continuous Access journal device group between DC2 and
DC3, and a phantom device group between DC1 and DC3.
NOTE: The phantom device group is a dummy device group which is used as a bridge to
access the remote site pair state. There is no pair created on this device group.
As it is required to configure three different device groups for a package, it is recommended
to follow a naming convention. The Continuous Access device group between DC1 and DC2
could be named as dg12<PackageName>. The Continuous Access device group between
DC2 and DC3 could be named as dg23<PackageName> and the Continuous Access device
group between DC1 and DC3 could be named as dg13<PackageName>.
For example, if an Oracle single instance package is configured in a 3DC environment,
dg12Oracle would be the name of Continuous Access device group between DC1 and
DC2, dg23Oracle would be the name of Continuous Access device group between DC2
and DC3, and dg13Oracle would be the name of the Continuous Access device group
between DC1 and DC3.
Edit the Raid Manager configuration file (horcm0.conf) in the above example to include
the devices and device group used by the application package. Only one device group may
be specified for all of the devices that belong to a single application package. These devices
are specified in the field HORCM_LDEV. Also complete the HORCM_INST field, supplying
the names of only those hosts that are attached to the P9000 or XP disk array that is remote
from the disk array directly attached to this host. The following are sample Raid Manager
configuration files given for each data replication configuration. In the sample configuration
files, the device groups names has been simplified for more clarity.
Multi-Target Bi-Link Raid Manager Configuration
For a Multi-Target Bi-Link configuration, the DC1, is configured as primary site of an application
and is the source of the data replicating to the DC2 and DC3. A sample Multi-Target Bi-Link
Configuration when using 3DC Sync/CAJ replication is as shown in Figure 78 (page 433). A
phantom device group is configured between DC2 and DC3.
432 Designing a Three Data Center Disaster Recovery Solution