Figure 13: Cluster Example Spanning Multiple c7000 Enclosures
| HP Systems Insight Manager (SIM) | Quorum Service (HP-UX OS) |
| Central Management Server (CMS) |
| |
| LAN | |
| VC Stacking Link |
| Serviceguard | |
| cluster | |
| SAN | |
| c7000 BladeSystem | c7000 BladeSystem |
| Enclosure | Enclosure |
EVA
Disk Array
In this example, a single 8-node Serviceguard cluster spans two c7000 enclosures, with 4 nodes in each enclosure attached to shared storage provided by an EVA disk array. A Virtual Connect stacking link is used between the enclosures to provide a private cluster heartbeat network between the enclosures. A Systems Insight Manager Central Management Server is used to provide overall management of the systems environment; however this server is not part of the Serviceguard cluster.
Note that it is permissible to mix server blades with other external physical or virtual (i.e., nPar, vPar, HP Integrity Virtual Machine) Serviceguard nodes in this configuration. However; no enclosure or complex can contain more than half of the cluster nodes (e.g., server blades, nPars), and requires an external quorum server to maintain cluster quorum in the event of a blade enclosure failure. A quorum service, running on a small HP-UX system in this example, is located outside of the blade enclosures to serve as a tie-breaker in case of an enclosure failure to allow the remaining 50% of the surviving cluster nodes to successfully form a new cluster. Additional information on Serviceguard cluster quorum requirements is available in the white paper titled “HP Serviceguard Cluster Configuration for HP-UX 11i or Linux Partitioned Systems” posted at http://docs.hp.com/en/6033/HPServiceguardClusterConfig_WP.pdf.
Advantages and Other Considerations
Having a Serviceguard cluster span multiple c7000 enclosures or other non-blade cluster nodes has many advantages over a “cluster in a box” configuration, and few limitations: