You can add storage to a VM by attaching an existing virtual disk.
Select the VM in the
pane, click on the
tab, and then
Attach. Alternatively, on the Storage menu, click Virtual Disks then Attach Virtual Disk.
Select a virtual disk from the list.
To set access to the virtual disk to read-only, select the
Attach as read-only
check box. This can help prevent data from being overwritten or
changed when the disk is accessed by more than one VM and allows
the virtual disk to be attached to many VMs. To allow write access
to the virtual disk, clear the check box.
Tip: problems on an underlying SR can sometimes cause an attached
virtual disk to become deactivated ("unplugged"). If this happens,
you should be able to activate it again from the VM's
tab by selecting it and clicking