HP Serviceguard manual Redundant Power Supplies, Larger Clusters

Figure 7 Cluster with Fibre Channel Switched Disk Array

This type of configuration uses native HP-UX or other multipathing software; see “About Multipathing” (page 33).

Redundant Power Supplies

You can extend the availability of your hardware by providing battery backup to your nodes and disks. HP-supported uninterruptible power supplies (UPS), such as HP PowerTrust, can provide this protection from momentary power loss.

Disks should be attached to power circuits in such a way that mirror copies are attached to different power sources. The boot disk should be powered from the same circuit as its corresponding node.

In particular, the cluster lock disk (used as a tie-breaker when re-forming a cluster) should have a redundant power supply, or else it can be powered from a supply other than that used by the nodes in the cluster. Your HP representative can provide more details about the layout of power supplies, disks, and LAN hardware for clusters.

Many current disk arrays and other racked systems contain multiple power inputs, which should be deployed so that the different power inputs on the device are connected to separate power circuits. Devices with two or three power inputs generally can continue to operate normally if no more than one of the power circuits has failed. Therefore, if all of the hardware in the cluster has 2 or 3 power inputs, then at least three separate power circuits will be required to ensure that there is no single point of failure in the power circuit design for the cluster.

Larger Clusters

You can create clusters of up to 16 nodes with Serviceguard. Clusters of up to 16 nodes may be built by connecting individual SPUs via Ethernet.

The possibility of configuring a cluster consisting of 16 nodes does not mean that all types of cluster configuration behave in the same way in a 16-node configuration. For example, in the case of shared SCSI buses, the practical limit on the number of nodes that can be attached to the same shared bus is four, because of bus loading and limits on cable length. Even in this case, 16 nodes

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