Here is adding new disk to XenServer

1. Login to Console
2. fdisk -l to identify which one is the disk, for example /dev/sdb
3. enter following command –

xe sr-create name-label=<Name of Storage> shared=false device-config:device=<Path of the Storage device> type=lvm

Or :
xe sr-create name-label=sdb-disk shared=false device-config:device=/dev/sdb type=lvm