Clustering Linux Servers with the Concurrent Deployment of HP Serviceguard Linux and Red Hat Global File System for RHEL5, October 2008

Conclusions

HP Serviceguard for Linux and Red Hat GFS for RHEL5 clusters can co-exist on the same set of

servers adding value to each other. Serviceguard can provide HA encapsulation to multiple

instances of the same application managing single instance of data from multiple nodes in the

cluster simultaneously. Stable co-existence of the two clusters can be achieved with a proper

choice of redundant hardware and software components and configurations as mentioned below.

¾ Use two FC links on all cluster nodes for external shared storage with two FC HBA, and

multipathing configured.

¾ Configure and run a disk monitoring service on all the packages in the dual-cluster. This

ensures that the packages are moved to other adoptive nodes when access to shared

storage is lost as a result of FC link failure.

¾ Use redundant heartbeat networks for Serviceguard and Red Hat GFS (via channel-

bonding).

¾ Asymmetric Red Hat cluster configurations can bring down the complete cluster. Hence

such configurations are not supported.

¾ For Serviceguard, it is recommended to use default heartbeat and the node timeout

values. For Red Hat cluster, it is recommended to slow down the failure detection by

increasing the totem token value from 5 seconds (default) to 28 seconds. In case of

network partition in a 2 node cluster, this recommendation will prevent nodes from

fencing each other, and hence preventing losing the whole cluster.

¾ Create Serviceguard package control scripts to allow the file systems to be mounted at all

times.

Terms

CLVM

Cluster volume manager provides cluster-wide version of LVM2

CMAN

The Cluster Manager is responsible managing the cluster quorum and keeps track of the

cluster membership

CCS

The Cluster Configuration System manages the cluster configuration and provides

configuration information to other cluster components in a Red Hat Cluster.

DLM

Distributed Lock Manager where the lock management responsibility is distributed across

all nodes of the cluster

Fiber channel

GFS