Duplicated form GIS StackExchange:
I would like to deploy between 4 and 5 ArcGIS Server 10.2.1 instances with different licenses on one machine. Can this be accomplished by pointing the server to different ports via the web adaptor or another method? I would also have other 3rd party applications on this physical machine with 1-3 virtual machines. The ideal configuration would be a RAID with 32 Gigs of RAM on one physical machine.
As commented in the GIS Stack Exchange question, No. ArcGIS for Server is designed to be deployed as multiple nodes servicing one site, not as multiple sites in one machine.
Even if you deployed one VM for each server, you couldn't get much use out of a VM server with only 32Gb RAM (especially if you wanted more than one service in each site). You can actually model the behavior of this configuration using the Capacity Planning Tool (it won't be pretty).