Configuration requirements for all Extended Distance Clusters

Refer to tables Table 2-2,Table 2-3and Table 2-4for information about the Products, Product revisions, Volume Managers supported in Extended Clusters.

The network interfaces used for cluster nodes must support DLPI¹. The network switches used in the configuration must also support DLPI. DLPI support is not required for Quorum Server nodes.

There can be separate TCP/IP networking links and Fibre Channel data links between the data centers, or both TCP/IP networking and Fibre Channel data can go over common WDM² (Wave Division Multiplexing), SONET or SDH links between the data centers. See the section below “TCP/IP Network and Fibre Channel Data links between the data centers” for more detail.

A minimum of two heartbeat paths must be configured for all cluster nodes. The preferred solution is two separate heartbeat subnets configured in the cluster, each going over a separately routed network path to the other data centers. Or, there can be a single dedicated heartbeat subnet with a Primary and Standby LANs configured for it, each going over a separately routed ³ network path to the other data centers. For clusters using CVM 3.5, only a single heartbeat subnet is supported, so you must have both Primary and Standby LANs configured for the heartbeat subnet on all nodes. Multiple heartbeat subnets are supported with LVM, SLVM, VxVM, CVM 4.1, CFS 4.1, CVM 5.0, and CFS 5.0. For EC RAC clusters, it is recommended to have an additional network for Oracle RAC cache fusion traffic. It is acceptable to use a single Standby network to provide backup for both the heartbeat network and the RAC cache fusion network, however it can only provide failover capability for one of these networks at a time. The RAC CRS heartbeat should go over the same network interfaces as the Serviceguard heartbeat, however CRS only supports one heartbeat (primary:standby pair).

	NOTE: 1–The Data Link Provider Interface (DLPI) is an industry standard definition for message communications to a STREAMS based network interface driver. The DLPI resides at layer 2, the data link layer, in the OSI Reference Model. 2–WDM stands for Wavelength Division Multiplexing. There are two WDM technology solutions: CWDM (Coarse Wavelength Division Multiplexing) and DWDM (Dense Wavelength Division Multiplexing). CWDM is similar to DWDM but is less expansive, has fewer channels, is less expandable, and works over a distance of 100 km. 3–By separately routed network path, we mean a completely independent, physically separate path, such that the failure of any component in one network path will not result in a network partition between any nodes in the cluster. In the case of fault tolerant WDM boxes, there may be a single common WDM box in the data center. There should be separate fibers routed independently between the WDM boxes in each data center, however.

Serviceguard requires that the Heartbeat subnets are common to all data centers, with the exception of Cross-Subnet configurations (see the next bullet for details on Cross-Subnet configurations).

Cross-Subnet configurations are supported with Extended Cluster configurations with up to 16 nodes. This allows the nodes in each data center to configure their heartbeats on subnets that are locally unique to their own data centers. The heartbeats must be statically routed; static route entries must be configured on each node to route the heartbeats through different paths. Network routing must be configured between a minimum of two pairs of subnets between the data centers, and the routing between each subnet pair must be configured such that the failure of a single router or LAN segment will not take out all heartbeats between the data centers. There must be a minimum of 2 heartbeat subnets in each data center and each heartbeat subnet must have a Standby subnet. The heartbeat between the data centers requires TCP/IP connectivity (I.E. DLPI connectivity is not required between the data centers, but is required within the data centers). SGeRAC, CVM and CFS are not supported in Cross-Subnet cluster configurations. All other requirements listed in this section still apply for Cross-Subnet configurations, unless otherwise noted.

There must be less than 200 milliseconds of roundtrip latency in the link between the data centers. This latency requirement applies for both the heartbeat network and the Fiber Channel data.

Fibre Channel Direct Fabric Attach (DFA) is recommended over Fibre Channel Arbitrated loop configurations, due to the superior performance of DFA, especially as the distance increases.

Any combination of the following Fibre Channel capable disk arrays may be used: HP StorageWorks Disk Array XP, HP StorageWorks Enterprise Virtual Array (EVA), HP StorageWorks 1500cs Modular Smart Array (Active/Active controller version only), HP StorageWorks 1000 Modular Smart Array (Active/Active controller version only) or EMC Symmetrix Disk Arrays. Make sure to check with HP StorageWorks Division (SWD) to determine if they will support your desired combination of disk arrays to be connected to the same Host Bus Adapter.

The use of MirrorDisk/UX with LVM or SLVM, or software mirroring with VxVM or CVM is required to mirror the application data between the Primary data centers. Devices with Active/Passive controllers are not supported with VxVM or CVM mirroring, therefore only LVM or Shared LVM and MirrorDisk/UX are supported for the mirroring between the data centers with these devices.

Concurrent disk access with EC RAC is supported only with Shared LVM Volume Groups or CVM 3.5, 4.1 or 5.0 disk groups or CFS 4.1 or 5.0. EC RAC supports 2 nodes for distances of up to 100 kilometers. EC RAC is supported on 2, 4, 6 or 8 nodes for distances of up to 10 kilometers with CVM 3.5, CVM 4.1, CFS 4.1, CVM 5.0 or CFS 5.0 (SLVM supports a maximum of 2 nodes).

VxVM/CVM mirroring is supported in Extended Clusters for distances of up to 100 kilometers. CFS relies on CVM mirroring. See the Special requirements and recommendations for using VxVM, CVM and CFS in Extended Clusters below for more information using these in Extended Clusters.

An Extended Cluster may contain any combination of physical nodes, nPar nodes, vPar nodes and HP Integrity Virtual Machine (HPVM) nodes. For more information on configuration of nPar, vPar and HPVM nodes in clusters.

	NOTE: Refer to the documents “HP Serviceguard Cluster Configuration for HP UX 11i or Linux Partitioned Systems” and “Designing High Availability Solutions using HP Integrity Virtual Machines”, located at http://docs.hp.com