To prevent packages from being started at the wrong time and in the wrong place, use the following strategies:
•Set the AUTO_RUN (PKG_SWITCHING_ENABLED used prior to Serviceguard A.11.12) parameter for all primary and recovery packages to NO.
•Ensure that recovery package names are well known, and that personnel understand they should never be started with a cmrunpkg or cmmodpkg command unless the cmrecovercl command has been invoked first.
•If a cluster has no packages to run before recovery, then do not allow packages to be run on that cluster with Serviceguard Manager.
Network Attributes
Another important difference between the packages configured in Continentalclusters and the packages configured in a standard Serviceguard cluster is that the same or different subnets can be used for primary cluster and recovery cluster configurations. In addition, the same or different relocatable IP addresses can be used for the primary package and its corresponding recovery package. The client application must be designed properly to connect to the appropriate IP address following a recovery operation. For recovery groups with a rehearsal package configured, ensure that the rehearsal package IP address is different from the recovery package IP address.
How Serviceguard commands work in a Continentalclusters
Continentalclusters packages are manipulated manually by the user via Serviceguard commands and by cmcld automatically in the same way as any other packages.
In Continentalclusters the recovery package is not allowed to run at the same time as the primary, data sender, or data receiver packages. To enforce this, several Serviceguard commands behave in a slightly different manner when used in Continentalclusters.
Table 8 describes the Serviceguard commands whose behavior is different in Continentalclusters environment. Specifically, when one of the commands listed in Table 8 attempts to start or enable switching of a package, it first checks the status of the other packages in the recovery group. Based on the status, the operation is either allowed or disallowed.
The checking is done based on the stable clusters' environment and the proper functioning of the network communication. In the case when the network communication between clusters can not be established or the cluster or package status can not be determined, it must be checked manually to ensure that the operation to be performed on the target package will not have a conflict with other packages configured in the same recovery group.
Table 8 Serviceguard and Continentalclusters Commands
Commands | How the commands | How the commands work in Continentalclusters |
| work in Serviceguard |
|
|
|
|
cmrunpkg | runs a package | Will not start a recovery package if any of the primary, data receiver, |
|
| or data sender package in the same recovery group is running or |
|
| enabled. Will not start recovery package if the recovery group is in |
|
| maintenance mode. Will not start a primary, data receiver, or data |
|
| sender package if the recovery package in the same recovery group is |
|
| running or enabled. Will not start a rehearsal package when the |
|
| recovery group is not in maintenance mode. |
|
|
|
cmmodpkg | enable switching | Will not enable switching on a recovery package if any of the primary, |
| attribute for a highly | data receiver, or data sender package in the same recovery group is |
| available package | running or enabled. Will not enable switching for a recovery package |
|
| if the recovery group is in maintenance mode. Will not enable a primary, |
|
| data receiver, or data sender package if the recovery package in the |
|
| same recovery group is running or enabled. Will not enable switching |
|
| for a rehearsal package when the recovery group is not in maintenance |
|
| mode. |
|
|
|
Understanding Continentalclusters Concepts | 47 |