Even though Windows Server 2003 has gone into end of support since July 2015, I still find their existence in my customer environment. Last week, a performance issue raised by one of my customer, where it related with application running on Windows Server 2003. The application just migrated from physical to virtual about 2 weeks before the application team observed slower performance during end of month process. When migrated, they changed the configuration from 2 CPU socket x 4 cores/socket into 4 CPU vSocket x 4 vCores/vSocket. Related to that change, my first thought, do we hit any maximum CPU limit? What is the maximum CPU on Windows Server 2003? This article is a self note about maximum CPU supported on Windows Server 2003.
Remember that Windows Server 2003 released in the era where the standard is single core CPU. Looking at the official document from Microsoft such as this document shows the supported Symmetric Multiprocessing (SMP) each edition of Windows Server 2003. For instance, Windows Server 2003 Standard Edition support 4-way SMP. Now the question is what’s defined as 4-way SMP? I found this VMware kb article which says that 4-way SMP means 4 CPU socket (or 4 vSocket in vSphere environment).