SnapLock volumes cannot be created in an active/active configuration if one node is running on the first release of Data ONTAP 7.3 and the other node is running on Data ONTAP 7.3.1. This is because the first release of Data ONTAP 7.3 does not support SnapLock.
For example, consider an active/active configuration with two nodes, node A running on Data ONTAP 7.3.1 and node B running on Data ONTAP 7.3. In addition, node A contains SnapLock volumes. If node A goes down, the disks of node A are taken over by the disks of node B. However, due to the presence of the SnapLock volumes, node B halts.
Therefore, to enable the creation of new SnapLock volumes in an active/active configuration, you need to upgrade both the nodes to Data ONTAP 7.3.1.