Features
| Name | Guest OS SMP available | Runs arbitrary OS | Supported guest OS drivers | Method of operation | Typical use | Speed relative to host OS | Commercial support available |
|---|---|---|---|---|---|---|---|
| Containers, or Zones | Yes, over 500-way on current systems | No | Uses native device drivers | Operating system-level virtualization | Server consolidation with workload isolation, single workload containment, hosting, dev/test/prod | Near native | Yes |
| Hyper-V Server 2008 R2 | Yes, up to 4 VCPUs per VM | Yes | Yes | Virtualization | Server consolidation, service continuity, dev/test, desktop virtualization, cloud computing | Up to near native | Yes |
| OpenVZ | Yes | No | Compatible | Operating system-level virtualization | Virtualized server isolation | Up to near native | ? |
| KVM | Yes | Yes | Yes | AMD-V and Intel-VT-x | Virtualized server isolation, server/desktop consolidation, software development, cloud computing, other purposes | Up to near native | Yes, Look at RedHat or Novell for details |
| Linux-VServer | Yes | No | Compatible | Operating system-level virtualization | Virtualized server isolation and security, server consolidation, cloud computing | Up to near native | Yes |
| Oracle VM Server for x86 | Yes | Yes | Yes | Paravirtualization and hardware virtualization | Server consolidation and security, enterprise and business deployment | Up to near native | Yes |
| Oracle VM Server for SPARC | Yes | Yes, but needs porting | Yes | Paravirtualization and hardware virtualization | Server consolidation and security, enterprise and business deployment | Up to near native | Yes |
| OVPsim | Yes | Yes | ? | Full system simulation with optional component virtualization | Software development (early, embedded), advanced debug for single and multicore software, compiler and other tool development, computer architecture research, hobbyist | Depends on target architecture (full and slow hardware emulation for guests incompatible with host) | Yes, with commercial license from Imperas |
| PikeOS | Yes | Yes, but modifications required as paravirtualization is used | Yes | Paravirtualization | Safety and security critical embedded systems. | Up to near native | Yes |
| RTS Hypervisor | Yes | Yes | Yes, standard device drivers can be used without porting. | Virtualization in two modes: full virtualization and paravirtualization; guest OS can run in different modes concurrently | x86 based devices; focus is on real-time uses | Depends on guest | Yes |
| ScaleMP vSMP Foundation | Yes, up to 8,192 CPUs and 64 TB per VM | Yes | Yes | Virtualization | Server consolidation, Cloud computing | ? | Yes |
| Safe Virtual Machine Altreonic | Not applicable | Runs on any OS | OpenComRTOS all services | Interpreter | Executes binary code on any embedded processor, diagnostics, dynamic code loading, 3KB code size | Depends on application but slow due to its interpreting nature | Yes |
| Simics | Yes | Yes | Yes | Full system simulation of processors, MMUs, devices, disks, memories, networks, etc. | Software development, advanced debug for single and multicore software, compiler and other tool development, computer architecture research, bug transportation, automated testing, system architecture, long-term support of safety-critical systems, early hardware availability, virtual prototyping | Depends on host machine and target architecture. Runs at near-native speeds for x86-on-x86 using VT-x, cross-simulation of other architectures can be faster or slower than real-time depending on how fast the target is and how big the target is (number of processors, number of target machines, and how much the simulation can be parallelized) | Yes |
| Sun xVM Server | Yes | Yes | Yes | Paravirtualization and porting or hardware virtualization | Servers, Development | Up to near native | Yes |
| SVISTA 2004 | No | ? | ? | ? | Hobbyist, Developer, Business workstation | ? | ? |
| TRANGO | Yes | Yes | Yes | Paravirtualization and porting or hardware virtualization | Mob. phone, STB, routers, etc. | Near native | ? |
| User Mode Linux | ? | No | special guest kernel+modules required | Porting | Developer (as a separate machine for a server or with X11 networking) | Non-significantly slower than native (all calls to kernel are proxied) | ? |
| Oracle VirtualBox | Yes | Yes | Yes | Virtualization | Business workstation, server consolidation, service continuity, developer, hobbyist | Up to near native | Yes (with commercial license) |
| Virtual Iron 3.1 | Yes, up to 8 way | Yes | Yes | Native virtualization | Server consolidation, service continuity, dev/test | ? | Yes |
| Virtual PC 2007 | No | Yes | Yes | Virtualization, guest calls trapping where supported | Hobbyist, Developer, Business workstation | Up to near native with virtual machine additions | ? |
| Windows Virtual PC | Yes | Yes | Yes | Hardware virtualization | Developer, Business workstation, support for Compatibility with Windows XP applications | Up to near native with virtual machine additions | No |
| Virtual PC 7 for Mac | No | Yes | Yes | dynamic recompilation (guest calls trapping where supported) | Hobbyist, Developer, Business workstation | Slow | ? |
| Virtual Server 2005 R2 | No | Yes | Yes | Virtualization (guest calls trapping where supported) | Server, server farm | Up to near native with virtual machine additions but slower than with hypervisor due to proxied calls | ? |
| CoWare Virtual Platform | Yes | Yes | Yes ( Same compiled Software image as for the real device) | Full-system virtualization (Processor Core ISA + Hardware + External connections) | Early embedded software development and integration (from driver to application), Multi-core software debugging and optimization | Depending on the system characteristics and the software itself, ranges from faster than real time to slow. | Yes |
| Virtuozzo | Yes | No | Compatible | Operating system-level virtualization | Server consolidation, service continuity, disaster recovery, service providers | Up to near native | Yes |
| VMware ESX Server 4.0 (vSphere) | Yes, add-on, up to 8 way | Yes | Yes | Virtualization | Server consolidation, service continuity, dev/test, cloud computing | Up to near native | Yes |
| VMware ESX Server 3.0 | Yes, add-on, up to 4 way | Yes | Yes | Virtualization | Server consolidation, service continuity, dev/test | Up to near native | Yes |
| VMware ESX Server 2.5.3 | Yes, add-on, 2 way | Yes | Yes | Virtualization | Server consolidation, service continuity, dev/test | Up to near native | Yes |
| VMware Fusion | Yes | Yes | Yes | Virtualization | Hobbyist, Developer, Tester, Business workstation | Up to near native | Yes |
| VMware Server | Yes (2-way) | Yes | Yes | Virtualization | Server/desktop consolidation, dev/test | Up to near native | Yes |
| VMware Workstation 6.0 | Yes (2-way) | Yes | Yes | Paravirtualization (VMI) and virtualization | Technical professional, advanced dev/test, trainer | Up to near native | Yes |
| VMware Player 2.0 | Yes (2-way) | Yes | Yes | Virtualization | Technical professional, advanced dev/test, trainer, end user on prebuilt machines | Up to near native | Yes |
| Wind River hypervisor | No | Yes | Yes | Paravirtualization, hardware assisted virtualization | Embedded, safety critical, secure | Up to near native | Yes |
| Wind River VxWorks MILS Platform | No | Yes | Yes | Paravirtualization, hardware assisted virtualization | Embedded, safety critical, secure | ? | Yes |
| Xen | Yes, v4.0.0: up to 128 VCPUs per VM | No, bare hypervisor | Yes | Paravirtualization and porting or hardware virtualization. Runs on x86, ARM. | Virtualized server isolation, server/desktop consolidation, software development, cloud computing, other purposes. Xen powers most public cloud services and many hosting services, such as Amazon Web Services, Rackspace Hosting and Linode. | Up to native | Yes |
| XtratuM | Yes | No | Yes | Paravirtualization | Embedded, safety critical, secure | ? | Yes |
| Xvisor | No | Yes | Yes | Full virtualization and Hardware assisted virtualization | Embedded systems | Up to near native | No |
| z/VM | Yes, both real and virtual (guest perceives more CPUs than installed), incl. dynamic CPU provisioning and reassignment | Yes | Yes, but not required | Virtualization (among first systems to provide hardware assists) | Servers | Near Native | Yes |
| z LPARs | Yes, both real and virtual (guest perceives more CPUs than installed), incl. dynamic CPU provisioning and reassignment; up to 64 real cores | Yes | Yes, but not required | Microcode and hardware hypervisor | Servers | Native: System z machines always run with at least one LPAR | Yes |
| Name | Guest OS SMP available | Runs arbitrary OS | Supported guest OS drivers | Method of operation | Typical use | Speed relative to host OS | Commercial support available |
- ^ Providing any virtual environment usually requires some overhead of some type or another. Native usually means that the virtualization technique does not do any CPU level virtualization (like Bochs), which executes code more slowly than when it is directly executed by a CPU. Some other products such as VMWare and Virtual PC use similar approaches to Bochs and QEMU, however they use a number of advanced techniques to shortcut most of the calls directly to the CPU (similar to the process that JIT compiler uses) to bring the speed to near native in most cases. However, some products such as coLinux, Xen, z/VM (in real mode) do not suffer the cost of CPU-level slowdowns as the CPU-level instructions are not proxied or executing against an emulated architecture since the guest OS or hardware is providing the environment for the applications to run under. However access to many of the other resources on the system, such as devices and memory may be proxied or emulated in order to broker those shared services out to all the guests, which may cause some slow downs as compared to running outside of virtualization.
- ^ OS-level virtualization is described as "native" speed, however some groups have found overhead as high as 3% for some operations, but generally figures come under 1%, so long as secondary effects do not appear.
- ^ See for a paper comparing performance of paravirtualization approaches (e.g. Xen) with OS-level virtualization
- ^ Requires patches/recompiling.
- ^ Exceptional for lightweight, paravirtualized, single-user VM/CMS interactive shell: largest customers run several thousand users on even single prior models. For multiprogramming OSes like Linux on zSeries and z/OS that make heavy use of native supervisor state instructions, performance will vary depending on nature of workload but is near native. Hundreds into the low thousands of Linux guests are possible on a single machine for certain workloads.
Read more about this topic: Comparison Of Platform Virtual Machines
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