How the Data Replication Subsystem Verifies the Device Group

The device group that Sun StorageTek Availability Suite controls is added to a protection group. The data replication layer verifies that the device group exists and that the value of its Nodelist property contains the same entries in identical order to the Nodelist property of the protection group.

When the geopg add-device-group command runs, a lightweight resource group for the device group is created and brought online. The lightweight resource group contains the following resources:

• A logical hostname resource that is used for data replication, as specified in the Local_logical_host property

• An HAStoragePlus resource that controls the collocation of the device group with the lightweight resource group

For more information about lightweight resource groups and their resources, see Sun StorageTek Availability Suite Lightweight Resource Groups.

When you run the geopg add-device-group command, a replication resource of the type GeoCtlAVS is created in the replication resource group of each device group in the protection group and brought online. For information about the format of the replication resource group, see Sun StorageTek Availability Suite Replication Resource Groups.

The Nodelist property of the lightweight resource group and replication resource group contains the same entries in identical order to the Nodelist property of the protection group.

If a resource or resource group of the same name is already configured on the local cluster, Sun Cluster Geographic Edition verifies the configuration and sets the Configuration to Error if the configuration is not correct.

If the Enable_volume_set property of this device group is set to True, then volume sets that are defined in the /var/cluster/geo/avs/AVS-devicegroup-volset.ini file are enabled. Otherwise, Sun Cluster Geographic Edition software controls and monitors all volume sets that you enable manually by using the Sun StorageTek Availability Suite commands.

If the geopg add-device-group command is unsuccessful, the configuration of the protection group is not modified.

If the geopg add-device-group command is successful and the Configuration status on the local cluster is set to OK, then the new configuration is propagated to the partner cluster. This propagation causes the whole protection group configuration to revalidate on the partner cluster. During revalidation, the same entities are created on the partner cluster, including the lightweight resource group and the replication resource group. Volume sets are also enabled on the partner clusters if the /var/cluster/geo/avs/AVS-devicegroup-volset.ini file exists on the partner cluster and contains correctly defined volume sets. If the validation is unsuccessful, then the Configuration status on the partner cluster is set to Error on the partner cluster.

Do not use Sun Cluster commands to change, remove, or bring offline these resources or resource groups. Use only Sun Cluster Geographic Edition commands to administer lightweight resource groups, replication resource groups, and resources that are internal entities managed by Sun Cluster Geographic Edition software. Altering the configuration or state of these entities directly with Sun Cluster commands could result in unrecoverable failure.

If the device group on the partner cluster is validated successfully and the Enable_volume_set property of this device group is set to true, then the volume sets that are defined in the /var/cluster/geo/avs/AVS-devicegroup-volset.ini file are enabled on the partner cluster. Other volume sets of the device group are disabled.

After the device group has been added to the protection group, you can enable or disable the volume sets of the device group directly by using the Sun StorageTek Availability Suite commands. The /var/cluster/geo/avs/AVS-devicegroup-volset.ini file is used only when the protection group that contains the device group is successfully validated for the first time.