Stretch Clusters Vs. Cluster Of Clusters - Novell BUSINESS CONTINUITY CLUSTERING 1.2 - ADMINISTRATION Administration Manual

Table 1-1 compares the benefits and limitations of host-based and storage-based mirroring.
Comparison of Host-Based and Storage-Based Data Mirroring
Table 1-1
Capability
Geographic distance between
sites
Mirroring the SBD partition
Synchronous data-block
replication of data between sites
Failover support
Failure of the site interconnect
SMI-S compliance

1.2.3 Stretch Clusters vs. Cluster of Clusters

A stretch cluster and a cluster of clusters are two clustering implementations that you can use with
Novell Cluster Services
TM
each deployment type, then compares the capabilities of each.
Novell Business Continuity Clustering automates some of the configuration and processes used in a
cluster of clusters. For information, see
"Stretch Clusters" on page 15
"Cluster of Clusters" on page 16
"Comparison of Stretch Clusters and Cluster of Clusters" on page 17
"Evaluating Disaster Recovery Implementations for Clusters" on page 19
Stretch Clusters
A stretch cluster consists of a single cluster where the nodes are located in two geographically
separate data centers. All nodes in the cluster must be in the same Novell eDirectory
requires the eDirectory replica ring to span data centers. The IP addresses for nodes and cluster
resources in the cluster must share a common IP subnet.
Host-Based Mirroring
Up to 10 km
An SBD can be mirrored between
two sites.
Yes
No additional configuration of the
hardware is required.
LUNs can become primary at
both locations (split brain
problem).
If the storage subsystems are not
SMI-S compliant, the storage
subsystems must be controllable
by scripts running on the nodes of
the cluster.
to achieve your desired level of disaster recovery. This section describes
Section 1.3, "Business Continuity Clustering," on page
Storage-Based Mirroring
Can be up to and over 300 km.
The actual distance is limited only
by the SAN hardware and media
interconnects for your
deployment.
Yes, if mirroring is supported by
the SAN hardware and media
interconnects for your
deployment.
Yes, requires a Fibre Channel
SAN or iSCSI SAN.
Requires additional configuration
of the SAN hardware.
Clusters continue to function
independently. Minimizes the
chance of LUNs at both locations
becoming primary (split brain
problem).
If the storage subsystems are not
SMI-S compliant, the storage
subsystems must be controllable
by scripts running on the nodes of
the cluster.
tree, which
TM
Overview of Business Continuity Clustering
20.
15