Designing Disaster Tolerant High Availability Clusters, 10th Edition, March 2003 (B7660-90013)

Physical Data Replication for ContinentalClusters Using Continuous Access XP
Preparing the Continental Cluster for Data Replication
Chapter 6288
Preparing the Continental Cluster for Data
Replication
These procedures will prepare your MC/ServiceGuard clusters for use
with Continuous Access XP data replication in a continental cluster.
1. Ensure that the XP Series disk arrays are correctly cabled to each
host system in the two clusters that will run packages whose data
reside on the arrays.
Each XP Series disk array must be configured with redundant CA
links, each of which is connected to a different LCP or RCP card. To
prevent a single point of failure (SPOF), there must be at least two
physical boards in each XP for the CA links. Each board usually has
multiple ports. However, a redundant CA link must be connected to a
port on a different physical board from the board that has the
primary CA link. When using bi-directional configurations, where
data center A backs up data center B and data center B backs up
data center A, you must have at least four CA links, two in each
direction. Four CA links are also required in uni-directional
configurations in which you want to allow failback.
2. Install the Raid Manager XP software on each host system that has
data residing on the XP disk arrays.
3. Edit the /etc/services file, adding an entry for the Raid Manager
instance to be used with ContinentalClusters.
The format of the entry is:
horcm<instance-number> <port-number>/udp
For example:
horcm0 11000/udp #Raid Manager instance 0
For more detail, see the
/opt/cmcluster/toolkit/SGCA/Samples-CC/services.example
file.
4. Use the ioscan command to determine what devices on the XP disk
array have been configured as command devices. The device-specific
information in the rightmost column of the ioscan output will have
the suffix -CM for these devices; e.g., OPEN-3-CM.