There is no direct way to get the serial number of the backend array (that I'm aware of) - however, at least IBM and HDS arrays include the array serial number in the lun serial number, which can be viewed (per lun) with disk show or storage storage show. You have to filter off the actual lun identifier - for example, all my HDS luns are 8704xxxx00C1, 8704xxxx00C2, 8704xxxx00C3... In this case the array serial # is 8704xxxx, and the cu:ldev of the luns themselves are 00:c1, 00:c2, 00:c3...
You can take a look at your disk show output and compare it to your (hopefully known) serial numbers and see if you can do the same thing.
Hope that helps