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

Building a Metropolitan Cluster Using MetroCluster/CA
Designing a Disaster Tolerant Architecture for use with MetroCluster/CA
Chapter 380
* Cluster can be manually started with the remaining node.
Table 3-4 illustrates possible results if a data center fails in a
configuration with a single arbitrator.
* Cluster can be manually started with the remaining node.
With a single arbitrator node, the cluster is at risk each time a node fails
or comes down for planned maintenance.
nodes 1, 2, arbitrator 1, then
node 3
1 of 2 (50%) cluster halts*
arbitrator 1, then node 1 3 of 4 (75%) pkg A switches
Table 3-3 Node Failure Scenarios with One Arbitrator (Continued)
Failure Quorum Result
Table 3-4 Data Center Failure Scenarios with One Arbitrator
Failure Quorum Result
data center A (nodes 1 and 2) 3 of 5 (60%) pkg A and B
switch to data
center B
data center A, then arbitrator 1 2 of 3 (67%) pkg A and B
switch, then no
change
data center A and arbitrator 1 2 of 5 (40%) cluster halts*
data center A, then arbitrator 1,
then node 3
1 of 2 (50%) cluster halts*
arbitrator 1, then data center A 2 of 4 (50%) cluster halts*
node 3, then data center A 2 of 4 (50%) cluster halts*
data center B 3 of 5 (60%) pkg C and D
switch to data
center A
third location 4 of 5 (80%) no change