The New Partition wizard can only enumerate the first Windows partition, in mounted LUN volumes with multiple partitions.
Enterprise Vault implements Microsoft Cluster API calls via ClusterResourceControl.
The query issued by the wizard results in an incorrect interpretation of the drive letter for the mounted partitions to be enumerated.
The iSCSI mounted volumes should contain a single Windows partition.
This issue is resolved in the following release:
Enterprise Vault 9.0.4 Cumulative Hotfix 5 Release
Enterprise Vault 10.0.4 - Release Details
Enterprise Vault 9.0.5 - Release Details
Enterprise Vault (EV) installed as a clustered application in a Microsoft Failover Cluster using iSCSI or SAS mounted LUNs as shared storage
EV 9.0.x & EV 10.0.x
Windows 2008 Server