Specifications

52 Implementing UPS Configurations with Microsoft Cluster Server

Figure 51. Multiple UPS units with Redundant Switch

UPS fault tolerance is provided by two independent phases (A, B) powering two

pairs of UPS units. Each pair is connected to an APC Redundant Switch, which

adds fault-tolerance in case one of the UPS or power line fails. UPS monitoring is

replaced by monitoring of the Redundant Switches.

In the case of using different power phases in the same data center (Phase A =

Phase A’ and Phase B = Phase B’), the UPS software is installed in the same way

as for a single power line solution (3.2, “Single power line solutions” on page 31).

The only situation which affects the cluster is loss of all power. Thus the server

status is always the same for both nodes.

This solution has not been tested during our project, and we will not discuss

further details here.

3.3.2 Solution with two UPS units

The power cabling from Figure 52 on page 53 is often used in cluster

configurations. The advantage is that — similar to the use of a Redundant Switch

in the previous section — failure of one power line is hidden from the cluster.

Cluster

UPS 1

UPS 2

Power

Phase A

Phase B

Redundant

Switch

Power

Server 1

UPS 3

UPS 4

Power

Phase A'

Phase B'

Redundant

Switch

Power

Server 2

Communication