You need access to the command line to type this command.
dadmin@S8500_COE> cat /etc/ecs.conf |grep -i servertype
ServerType ibmx305
ibmx305 = S8500A
ibmx306 = S8500B
ibmx306m = S8500C
xen = Virtual Platform
icc = S8300
ibmx305 = S8500A
ibmx306 = S8500B
ibmx306m = S8500C
isp2100 = S8700
dl380g3 = S8710
dl385g1 = S8720
hs20 = HS20 Blade
hs20_8832_vm = HS20 VM Blade
From Jamie on Determining Server Type #
dell1950 = S8510