Virtualization architecture consisting of a thin software layer that runs directly on the hardware intercepting some, or all, operating system calls to hardware. Typically the hypervisor virtualizes CPU and memory while a single priviledged guest is assigned to manage and virtualize network and disk. NUMA on- niform emory ccess systems are essentially SMP computers with multiple memory busses. As the acronym suggests, access to some regions of memory is quicker than to others. Most often each CPU will have a range of memory that is considered local, the operating system must optimize to keep memory for processes close to the CPU that is executing said program. OSS pen ource oftware refers to software that is made available in source code form and is usually free of charge. Not only is source code available but you are free to modify it for your own purposes and (in the case of some licenses) you may even resell OSS without any fees or royalties being owed to software's creator. Examples of OSS licenses are MPL, GPL and BSD. Refer to the Open Source Institute for a better definition.