Understanding and Designing Serviceguard Disaster Recovery Architectures

Figure 10 Two Data Centers and Third Location with Arbitrators or a Quorum Server
Node 1
Node 2
Network
Switch
Network
Switch
Network
Switch
Network
Switch
Network
Switch
Network
Switch
Arbitrator
Data Center A Data Center B
Third Location
Power
Circuit 5
Power
Circuit 6
Local XP
Disk Array
Remote XP
Disk Array
Power
Circuit 2
Power
Circuit 1
Power
Circuit 3
Power
Circuit 4
Node 1
Node 2
PV Links
PV Links
PV Links
PV Links
Arbitrator
Quorum
Server
replicated data for package B
replicated data for package A
PVOL --------------------------------------- SVOL
PVOL --------------------------------------- SVOL
replicated data for package C
replicated data for package D
SVOL --------------------------------------- PVOL
SVOL --------------------------------------- PVOL
Highly Available network
Continous Access Link
pkg B
pkg A
pkg C
pkg D
A
D
1
B
C
1
C
B
1
D
A
1
Main disk array for one set of packages can also be the remote disk array for another package.
In Figure 10 (page 23), the P9000 or XP disk array in data center A is the main or primary disk
array for packages A and B, and the remote or secondary disk array for packages C and D in
data center B. For packages A and B, data is written to disk A and disk B on the array in Data
Center A and replicated to disk A
1
and disk B
1
on the array in Data Center B. Similarly, P9000
or XP disk array in Data Center B is the primary or main disk array for packages C and D, and
the secondary or remote for packages A and B. For packages C and D, data is written to disk C
and disk D on the disk array in Data Center B and replicated to disk C
1
and disk D
1
in Data Center
A.
NOTE: Cluster lock devices are not supported as arbitrators because cluster locks cannot be
maintained across the replication link, such as Continuous Access, SRDF, or 3PAR Remote Copy.
In the Metrocluster environment, the same number of systems must be present in each of the two
data centers (Data Center A and Data Center B) whose systems are connected to the disk arrays.
Understanding Metrocluster 23