In hardware-assisted virtualization, the hardware provides architectural support that facilitates building a virtual machine monitor and allows guest OSes to be run in isolation. Hardware-assisted virtualization was first introduced on the IBM System/370 in 1972, for use with VM/370, the first virtual machine operating system.
In 2005 and 2006, "Intel and "AMD provided additional hardware to support virtualization. Sun Microsystems (now "Oracle Corporation) added similar features in their "UltraSPARC T-Series processors in 2005. Examples of virtualization platforms adapted to such hardware include "KVM, "VMware Workstation, "VMware Fusion, "Hyper-V, "Windows Virtual PC, "Xen, "Parallels Desktop for Mac, "Oracle VM Server for SPARC, "VirtualBox and "Parallels Workstation.
In 2006, first-generation 32- and 64-bit x86 hardware support was found to rarely offer performance advantages over software virtualization.
In paravirtualization, the virtual machine does not necessarily simulate hardware, but instead (or in addition) offers a special API that can only be used by modifying["clarification needed] the "guest" OS. For this to be possible, the "guest" OS's source code must be available. If the source code is available, it is sufficient to replace sensitive instructions with calls to VMM APIs (e.g.: "cli" with "vm_handle_cli()"), then re-compile the OS and use the new binaries. This system call to the "hypervisor is called a "hypercall" in "TRANGO and "Xen; it is implemented via a DIAG ("diagnose") hardware instruction in IBM's "CMS under "VM["clarification needed] (which was the origin of the term hypervisor). Examples include IBM's "LPARs, "Win4Lin 9x, Sun's "Logical Domains, "z/VM,["citation needed] and "TRANGO.
In operating-system-level virtualization, a physical server is virtualized at the operating system level, enabling multiple isolated and secure virtualized servers to run on a single physical server. The "guest" operating system environments share the same running instance of the operating system as the host system. Thus, the same "operating system kernel is also used to implement the "guest" environments, and applications running in a given "guest" environment view it as a stand-alone system. The pioneer implementation was "FreeBSD jails; other examples include "Docker, "Solaris Containers, "OpenVZ, "Linux-VServer, "LXC, AIX "Workload Partitions, Parallels Virtuozzo Containers, and "iCore Virtual Accounts.
Hardware virtualization disaster recovery
A "disaster recovery (DR) plan is good business practice for a hardware virtualization platform solution. DR of a virtualization environment can ensure high rate of availability during a wide range of situations that disrupt normal business operations. Continued operations of VMs is mission critical and a DR can compensate for concerns of hardware performance and maintenance requirements. A hardware virtualization DR environment involves hardware and software protection solutions based on business continuity needs, which include the methods described below.
- Tape backup for software data long-term archival needs
- This common method can be used to store data offsite but can be a difficult and lengthy process to recover your data. Tape backup data is only as good as the latest copy stored. Tape backup methods will require a backup device and ongoing storage material.
- Whole-file and application replication
- The implementation of this method will require control software and storage capacity for application and data file storage replication typically on the same site. The data is replicated on a different disk partition or separate disk device and can be a scheduled activity for most servers and is implemented more for database-type applications.
- Hardware and software redundancy
- Ensures the highest level of disaster recovery protection for a hardware virtualization solution, by providing duplicate hardware and software replication in two distinct geographic areas.
- "Application virtualization
- "Comparison of platform virtualization software
- "Desktop virtualization
- "Dynamic infrastructure
- "Instruction set simulator
- "Popek and Goldberg virtualization requirements
- "Virtual appliance
- "Virtualization for aggregation
- "Workspace virtualization
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