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

Building a Metropolitan Cluster Using MetroCluster/SRDF
Preparing a Cluster for MetroCluster/SRDF
Chapter 4 145
at Data Center A, and R2 volumes are at Data Center B. R1 volumes for
pkg C and pkg D are at Data Center B, and R2 volumes are at Data
Center A.
Figure 4-11 Bidirectional 2 by 2 Configuration
Grouping the Symmetrix Devices at Each Data Center
The use of R1/R2 devices in M by N configurations of multiple
Symmetrix frames is enabled by means of consistency groups. A
consistency group is a set of Symmetrix RDF devices that are configured
to act in unison to maintain the integrity of a database. Because
MetroCluster/SRDF works at the device group level, the consistency
group is implemented and managed as a single device group even though
it spans multiple Symmetrix frames. Consistency groups are managed
by the EMC PowerPath product. When PowerPath is installed, the
Symmetrix tracks the I/Os that are written to the devices in the
consistency group. If an I/O cannot be written to a remote Symmetrix
node3
pkg C
Data Center B
node5
Third Location
node2
node6
Data Center A
(Arbitrators)
node4
pkg D
node1
R1 for C & D
R2 for A & BR2 for C & D
BCVs
pkg A
pkg B
R1 for A & B