HP Serviceguard Heartbeat Subnet and Cluster Re-formation Time, Advantages of Easy Deployment

Advantages of Easy Deployment

•Quick and simple way to create and start a cluster.

•Automates security and networking configuration that must always be done before you configure nodes into a cluster.

•Simplifies cluster lock configuration.

•Simplifies creation of shared storage for packages.

Limitations of Easy Deployment

•Does not install or verify Serviceguard software

•Requires agile addressing for disks. See “About Device File Names (Device Special Files)” (page 80).

•cmpreparestg (1m) will fail if cDSFs and persistent DSFs are mixed in a volume group. See “About Cluster-wide Device Special Files (cDSFs)” (page 104) for more information about cDSFs.

•Does not configure access control policies.

•Does not install or configure firewall and related software.

•Does not support cross-subnet configurations.

•Does not configure packages.

•Does not discover or configure a quorum server (but can deploy one that is already configured).

•Does not support asymmetric network configurations (in which only a subset of nodes has access to a given subnet).

For more information and instructions, see “Using Easy Deployment” (page 161).

Heartbeat Subnet and Cluster Re-formation Time

The speed of cluster re-formation depends on the number of heartbeat subnets.

If the cluster has only a single heartbeat network, and a network card on that network fails, heartbeats will be lost while the failure is being detected and the IP address is being switched to a standby interface. The cluster may treat these lost heartbeats as a failure and re-form without one or more nodes. To prevent this, a minimum MEMBER_TIMEOUT value of 14 seconds is required for clusters with a single heartbeat network.

If there is more than one heartbeat subnet, and there is a failure on one of them, heartbeats will go through another, so you can configure a smaller MEMBER_TIMEOUT value.

NOTE: For heartbeat configuration requirements, see the discussion of the HEARTBEAT_IP parameter later in this chapter. For more information about managing the speed of cluster re-formation, see the discussion of the MEMBER_TIMEOUT parameter, and further discussion under “What Happens when a Node Times Out” (page 88) ,“Modifying the MEMBER_TIMEOUT Parameter” (page 192), and, for troubleshooting, “Cluster Re-formations Caused by MEMBER_TIMEOUT Being Set too Low” (page 333).

About Hostname Address Families: IPv4-Only, IPv6-Only, and Mixed Mode

As of A.11.19, Serviceguard supports three possibilities for resolving the nodes' hostnames (and Quorum Server hostnames, if any) to network address families:

•IPv4-only

•IPv6-only

•Mixed

106 Planning and Documenting an HA Cluster