How to let Proxmox see iSCSI storage increase?

This may be a more general linux question, but..

We have a Dell MD3200i iSCSI SAN, we recently increased the size of the RAID partition used by proxmox by adding in additional hard disks. this was completed through the MD3200i tools successfully.

How do we get Proxmox to see that the available size has increased?

Thanks,
Royce