Building Disaster Tolerant Serviceguard Solutions Using Metrocluster with EMC SRDF
Building a Metrocluster Solution with EMC SRDF
Chapter 5 325
Scenario 1: In this scenario, the package failover is due to host failure or
due to planned downtime maintenance. The SRDF links and the
Symmetrix frames are still up and running. Because the package startup
time will be longer if the swapping is done automatically, the user can
choose not to have the swapping done by the package and then manually
execute the swapping after the package is up and running on the R2 side.
Following is the manual procedure to swap the devices personalities and
change the direction of the data replication.
On the host that connects to the R2 side, use the following steps:
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 or 2, 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, leave the application running in the
secondary data center. 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 a 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