If you are talking about SAN connected storage, than you will need to follow the manuals on how to properly map, discover, and then mount the LUNs. All of this is convered in the block guides. It's different for each OS. SnapDrive can help with this if you have it, but there is a manual process for each OS. But you won't see the volumes in this case, just the LUNs.
In an NFS context, you can see volumes just by exporting them and mounting them up.