In this example, a 4-node Serviceguard cluster is configured in a single c7000 enclosure, with an EVA disk array used for shared storage between the cluster nodes. An HP Systems Insight Manager Central Management Server is also shown, which provides overall management of the systems environment from outside of the Serviceguard cluster. While this example shows 4 integrity server blades used as cluster nodes, it is also possible to use HP Integrity Virtual Machines as Serviceguard nodes. HP Virtual Connect (not shown in this figure) can be configured to provide a private cluster heartbeat network within the enclosure for the cluster nodes without requiring any external wiring or switches. A quorum service, running on a Linux OS in this example, provides quorum for the 4-node cluster. Note it is supported to use a cluster lock disk or lock LUN for a 2, 3 or 4-node configuration within a blade enclosure; however it is recommended to use a quorum service for clusters having 3 or mode nodes.

While this configuration is supported, it is not recommended because the blade enclosure is considered a single point of failure (SPOF) that could potentially fail and bring down the entire cluster. However; one recommended best practice shown in this diagram is the placement of the CMS on a system external to the blade enclosure so that it can remain functional for managing other systems in the environment in the event the blade enclosure is unavailable due to some firmware update operations requiring the entire enclosure to be down or a power failure of the enclosure.

Advantages and Limitations

This configuration has the following advantages and limitations:

Advantages:

∙Provides a completely self-contained Serviceguard cluster within a single enclosure

∙Internal cluster heartbeat network can be configured using Virtual Connect to eliminate additional network cabling and switches

∙Provides consistent management of server profiles using Virtual Connect with all cluster nodes within the blade enclosure

Limitations:

∙The blade enclosure is a single point of failure that can cause the entire cluster to go down

∙There are no nodes external to the cluster to failover workloads in the event of planned enclosure maintenance (e.g., Virtual Connect and / or Onboard Administrator firmware upgrades that require all blades in the enclosures to be shutdown)

Clustering across Multiple Blade Enclosures or non-Blade Servers

One architecture design for improving a “cluster in a box” configuration is to split the Serviceguard cluster nodes between multiple blade enclosures or other external Serviceguard cluster nodes to avoid having a single enclosure as a single point of failure (SPOF). Figure 13 is an example of this architecture with a Serviceguard cluster spanning multiple c7000 blade enclosures.

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