> not be limited to the four operating system images that VMWARE has VMware (www.VMware.com) has several products, each with their own (artificial between the products at least, though also related to the amount of resource exists on the hardware) limitations ranging from 1 (Express) up to 20 (ESX Server). (Your milage may vary, etc.)
z/VM comes in one flavor, capable of running from 1 to (just under) 99,999 guests, though practical limits will be lower (depending upon resource needs, as with the VMware product). I know of systems with significant 5-digit (small, single user ;-)guest counts, as well as systems with significant 3&4-digit guest counts (many of which are large, complex guests). Peace. -njg
