Table 8 Serviceguard and Continentalclusters Commands (continued)

Commands

How the commands

How the commands work in Continentalclusters

 

work in Serviceguard

 

 

 

 

cmhaltnode -f

halts a node in a

Will not re-enable switching on a recovery package if any of the primary,

 

highly available

data receiver, or data sender package in the same recovery group is

 

cluster

running or enabled. Will not re-enable a primary, data receiver, or data

 

 

sender package if the recovery package in the same recovery group is

 

 

running or enabled.

 

 

 

cmhaltcl -f

This command will halt

Will not re-enable switching on a recovery package if any of the primary,

 

daemons on all

data receiver, or data sender package in the same recovery group is

 

currently running

running or enabled. Will not re-enable a primary, data receiver, or data

 

systems

sender package if the recovery package in the same recovery group is

 

 

running or enabled.

Designing a Disaster Recovery Architecture for use with Continentalclusters

A recovery pair in Continentalclusters consists of two Serviceguard clusters. One functions as a primary cluster and the other functions as recovery cluster for a specific application. Prior to Continentalclusters version A.05.00, one recovery pair can be configured in Continentalclusters. Starting with Continentalclusters version A.05.00, a configuration of multiple recovery pairs is allowed.

In the multiple recovery pair configuration, more than one primary cluster (where the primary packages are running) can be configured to share the same recovery cluster (where the recovery package is running).

The key elements providing disaster tolerance in Continentalclusters recovery pair are:

•Mutual Recovery

•Serviceguard clusters

•Data replication

•Highly available WAN networking

•Data center processes and procedures coordinated between the two cluster sites

There is significant amount of latitude in selecting these elements for a configuration. It is recommended the choices are recorded on worksheets which can be reviewed and updated periodically.

Mutual Recovery

For mutual recovery, any cluster in Continentalclusters recovery pair may contain both primary and recovery packages for any recovery group. Recovery groups may be defined, for example, such that cluster A and cluster B contain recovery packages. In this case, cmrecovercl could be run on cluster B to recover packages from cluster A, or on cluster A to recover packages from cluster B.

Serviceguard Clusters

Each Serviceguard cluster in Continentalclusters provides high availability for an application at the local level at that particular site. For optimal performance and to assure adequate capacity on the recovery cluster, it is best to have similar hardware on both clusters. For example, if one cluster contains two systems with 1Gb of memory each, it is not a good idea to have a low-end system with 128 Mb of memory in the other cluster. Each cluster may have as many nodes as are permitted in an ordinary Serviceguard cluster, and each may be running packages that are not configured to fail over between clusters.

48 Designing Continentalclusters