Specifications

Chapter 3. UPS configurations for cluster 55
What should a node do with cluster resources that are owned at the time of a
power loss?
If the other node is in status Node Up, then this node is able to get the resources
from the failing node. Because each node losing power sets its status to Node
Paused, we avoid useless resource moves.
In any other case, the resources currently owned by the failing node must be
brought offline. By bringing resources offline we ensure that applications shut
down properly and we prevent unwanted failovers that would be aborted (causing
problems when restarting).
These different cases are handled by the command file UPS.CMD. The command
file is started by the Windows NT UPS service after a power failure. Depending
on whether one node or both nodes are on battery, either a resource move or a
cluster shutdown is performed.
3.3.3 Control flow in UPS.CMD
In the event of a UPS power loss, a delay (UPS On Battery Delay) is set. After
this delay, the UPS service starts the UPS.CMD command file with the parameter
UPSOnBattery.
The main task of the command file UPS.CMD is to call CLUSTER.EXE. This is a
Microsoft Cluster Server utility program installed during cluster setup that can be
used to administer clusters from the command prompt. The CLUSTER.EXE
parameters are described in the
Microsoft Cluster Server Administrator’s Guide .
We use this utility for three purposes:
• The local cluster node is paused. Pausing a node means that existing groups
and resources stay online, but groups and resources cannot be brought online
on this node. In this way, we ensure that a resource brought offline will not be
restarted for any reason. Also the cluster node status Node Paused is an
indicator for administrators that the command file takes control.
• Eventually, groups that are currently located on this node are brought offline.
There are two exceptions: the quorum disk cannot be brought offline. The
Cluster Group contains the cluster name and IP address that must remain
available for executing CLUSTER.EXE commands.
• Eventually, groups that are currently located on this node are moved to the
surviving node.
Details of the command file UPS.CMD are discussed in Chapter 4, “The
command file UPS.CMD” on page 67.
Finally the operating system will be shut down. After the period specified in UPS
Turn Off Delay, the servers will be powered off.