For @@servername, the Cluster Edition returns the name of the cluster, not the instance name. Use @@instancename to return the name of the instance.
In a non-clustered Adaptive Server environment, the value for @@identity changes for every record inserted. If the most recent record inserted contains a column with the IDENTITY property, @@identity is set to the value of this column, otherwise it is set to “0” (an invalid value). This variable is session-specific, and takes its value based on the last insert that occurred during this session.
In a clustered environment, multiple nodes perform inserts on tables, so the session-specific behavior is not retained for @@identity. In a clustered environment, the value for @@identity depends on the last record inserted in the node for the current session and not on the last record inserted in the cluster.
