Novell BUSINESS CONTINUITY CLUSTERING 1.2.1 - ADMINISTRATION Administration Manual page 17

Nodes in each cluster access only the storage systems co-located in the same data center. Typically,
data is replicated by using storage-based mirroring. Each cluster has its own SBD partition. The
SBD partition is not mirrored across the sites, which minimizes the chance for a split-brain problem
occurring when using host-based mirroring. For information about using mirroring solutions for data
replication, see Section 1.2.2, "Host-Based versus Storage-Based Data Mirroring," on page
In the cluster-of-clusters architecture shown in
hardware between two data centers that are geographically separated. If a disaster occurs in one data
center, the cluster in the other data center takes over.
Cluster of Clusters
Figure 1-2
Building A
Ethernet Switch
Server Server Server
1A 2A 3A
Fibre Channel
Switch
Fibre Channel
Disk Arrays
Cluster Site 1
Comparison of Stretch Clusters and Cluster of Clusters
Table 1-2 compares the capabilities of a stretch cluster and a cluster of clusters.
Comparison of Stretch Cluster and Cluster of Clusters
Table 1-2
Capability
Number of clusters
Number of geographically
separated data centers
eDirectory trees
Figure 1-2, the data is synchronized by the SAN
Two independent clusters at
geographically separate sites
WAN
eDirectory
IDM
Server
4A
SAN
Disk blocks
Stretch Cluster
One
Two
Single tree only; requires the
replica ring to span data centers.
Building B
Ethernet Switch
Server Server Server
1B 2B 3B
Fibre Channel
Switch
Fibre Channel
Disk Arrays
Cluster Site 2
Cluster of Clusters
Two or more
Two or more
One or multiple trees
Overview of Business Continuity Clustering
14.
Server
4B
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