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

Building a Metropolitan Cluster Using MetroCluster/SRDF
R1/R2 Swapping
Chapter 4176
1. Swap the personalities of the devices and mark the old R1 devices to
be refresh from the old R2 devices.
# symrdf -g <device_group> swap -refresh R1
2. After swapping is completed, the devices will be in Suspended state.
Next establish the device group for data replication from the new R1
devices to the new R2 devices.
# symrdf -g <device_group> establish
Scenario 2: In this scenario, two failures happen before the package fails
over to the secondary data center. The SRDF link fails; the package
continues to run and write data on R1 devices. Sometime later, the host
fails; the package then fails over to the secondary data center. In this
case, even if the AUTOSWAPR2 variable is set to 1, the package will not do
the R1/R2 swapping, which happens after the host in the primary data
center and the SRDF links are fixed. To minimize the application down
time, instead of failing the application back to the primary data center,
the user can leave the application running in the secondary data center,
and then manually swap the devices personalities and change the
direction of the data replication.
1. Swap the personalities of the devices and mark the old R1 devices to
be refresh from the old R2 devices.
# symrdf -g <device_group> swap -refresh R1
2. After swapping is completed, the devices will be in suspended state.
Next Establish the device groups for data replication from the new R1
devices to the new R2 devices.
# symrdf -g <device_group> establish
WARNING R1/R2 Swapping cannot be used in an M by N Configuration.