Stretch Clusters Vs. Cluster Of Clusters - Novell BUSINESS CONTINUITY CLUSTERING FOR NETWARE 1.1 - ADMINISTRATION Manual

1.2.1 Stretch Clusters vs. Cluster of Clusters

Stretch Clusters
A stretch cluster consists of one cluster in which the nodes in the cluster are located in
geographically separate areas. All nodes in the cluster must be in the same eDirectory™ tree. In this
architecture, the data is mirrored between two data centers that are geographically separated. All the
machines in both data centers are part of one cluster, so that if a disaster occurs in one data center,
the other automatically takes over.
Figure 1-1
Server 1
Fibre Channel
Cluster of Clusters
A cluster of clusters consists of two or more clusters in which each cluster is located in a
geographically separate area. A cluster of clusters provides the ability to fail over selected cluster
resources or all cluster resources from one cluster to another cluster. Typically, replication of data
blocks between SANs is performed by SAN hardware, but it can be done by host-based mirroring
for synchronous replication over short distances.
12 Novell Business Continuity Clustering 1.1 for NetWare Administration Guide
Section 1.2.3, "Usage Scenarios," on page 16
"Stretch Clusters" on page 12
"Cluster of Clusters" on page 12
"Implementation Comparison" on page 14
Stretch Cluster
Building A
Ethernet Switch
Server 2 Server 3
Switch
Fibre Channel
Disk Array
Site 1
8-node cluster stretched
between two sites
WAN
Cluster
Heartbeat
Server 4
SAN
Disk blocks
Building B
Ethernet Switch
Server 5 Server 6 Server 7
Fibre Channel
Switch
Fibre Channel
Disk Array
Site 2
Server 8