APC AP9606 Specifications download pdf (Page 39)

Chapter 3. UPS configurations for cluster 31

administrator intervention is useful to analyze the status of such components

before starting production systems.

• There is a possibility that a resource operation might be aborted by an

operating system shutdown. In case of an aborted operation, you cannot

accurately predict the status of all resources at the moment of restart.

• With Windows 2000, the power management differs from Windows NT 4.0. At

the end of an operating system shutdown, the machine is powered off

automatically. When power is reestablished, the server must be switched on

by pressing the power button.

3.2 Single power line solutions

The first thing to consider is that all electric power for the cluster is provided by

one power line (one phase). This may be done via one or two UPS units. (More

than two UPS units per two-node cluster should not be used because each server

can configure or monitor only one UPS at a time.) The only possible scenario is

the failure of this single power line causing shutdown of the cluster.

If one UPS is sufficient to supply the whole cluster, then the cabling schema is as

shown in Figure 20.

Figure 20. Single power line with one UPS

If two UPS units are necessary, then the power cabling for shared storage

equipment needs special attention. As described in Storage power cabling on

page 2, the wrong order of shared storage component failures may destroy RAID

arrays. Thus we have to ensure that all storage components will lose power at the

same moment. But the run time of the two UPS units is always different, even if

they are of the same type, with the same load attached, and with the same

shutdown parameters (because of aging effects).

Cluster

Phase A

UPS

Server 1

Server 2

Communication - Smart-signaling cable

Communication - Simple-signaling cable

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APC AP9606 Specifications Page 39