Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access EVA P6000 for Linux B.12.00.00

4 Understanding failover/failback scenarios
Metrocluster package failover/failback scenarios
This section discusses the package start up behaviors in various failure scenarios depending on
DT_APPLICATION_STARTUP_POLICY and replication mode. Table 6 describes the list of failover
scenarios.
NOTE: The first time failover to a node at a remote site has to be done with the Management
Server being active for the EVA array at the remote site.
Table 6 Replication Modes and Failover Scenarios
ResolutionDT_APPLICATION_STARTUP_POLICYReplication
Mode
Failover
Scenario
Data_Currency_PreferredAvailability_Preferred
N/ADR Group fails over and the package is started. The behavior is
not affected by the presence of the FORCEFLAG file.
Synchronous
or Enhanced
Asynchronous
Remote failover
during normal
operations
(planned
failover)
To forcefully start
up the package
DR Group does not fail over and
the package does not start.
DR Group fails over and the
package is started.
Synchronous
or Enhanced
Asynchronous
Remote failover
when CA link
down or when even though data
The following log message
appears in the package log:
The following log message
appears in the package log:
the primary site
fails
currency cannot
be determined,
Warning - Unable to get remote
DR group state because the CA
The role of the device group
on this site is "destination". The
create a
“FORCEFLAG”
link is down. The role of thestate of the replication link is
file in package
device group on this site isdown and the state of data
directory and
"destination". The state of themay not be current. Because
restart the
package.
replication link is down and the
state of data may not be current.
the package startup policy is
AVAILABILITY_PREFERRED, the
Because the package startupprogram will attempt to start
up the package. policy is
DATA_CURRENCY_PREFERRED,
the package is NOT allowed to
start up.
Restart the
package when
If the Merge operation completes before WAIT_TIME expires,
DR group is failed over and the package is started. Otherwise,
SynchronousRemote failover
during merging
the merge is
completed.
the DR Group does not failover and the package is not started.
There is no change in this behaviour even if the FORCEFLAG file
is present.
The following log message appears in the package log:
The DR Group is in merging state.
....
The WAIT_TIME has expired.
Error - Failed to failover and swap the role of the device group.
The package is NOT allowed to start up.
To forcefully start
up the package,
If the merge operation completes
before WAIT_TIME expires, then
Waits till WAIT_TIME for the
Merge operation to complete.
Enhanced
Asynchronous
create aDR Group fails over and theThe package is started even if
“FORCEFLAG”package is started. Otherwise,,
the package is not started up.
merge is not completed within
this time. file in package
The following log message
appears in the package log:
directory and
restart the
package.
28 Understanding failover/failback scenarios