A volume ID is a value assigned to represent the volume when it is mounted by NCP Server on an OES server. The Client for Open Enterprise Server accesses a volume by using its volume ID. Volume ID values range from 0 to 254. On a single server, volume IDs must be unique for each volume. In a cluster, volume IDs must be unique across all nodes in the cluster.
Unshared volumes are typically assigned low numbers, starting from 2 in ascending order. Volume IDs 0 and 1 are reserved. Volume ID 0 is assigned by default to volume SYS. Volume ID 1 is assigned by default to volume _ADMIN.
Cluster-enabled volumes use high volume IDs, starting from 254 in descending order. When you cluster-enable a volume, Cluster Services assigns a volume ID in the resource’s load script that is unique across all nodes in a cluster. You can modify the resource’s load script to change the assigned volume ID, but you must manually ensure that the new value is unique.
In a OES Business Continuity Clustering (BCC) cluster, the volume IDs of BCC-enabled clustered volumes must be unique across all nodes in every peer cluster. However, clustered volumes in different clusters might have the same volume IDs. Duplicate volume IDs can prevent resources from going online if the resource is BCC-migrated to a different cluster. When you BCC-enable a volume, you must manually edit its load script to ensure that its volume ID is unique across all nodes in every peer cluster. You can use the ncpcon volumes command on each node in every peer cluster to identify the volume IDs in use by all mounted volumes. Compare the results for each server to identify the clustered volumes that have duplicate volume IDs assigned. Modify the load scripts to manually assign unique volume IDs.