Editing History of operating systems (section)

==Rise of virtualization==
Operating systems originally ran directly on the hardware itself and provided services to applications, but with virtualization, the operating system itself runs under the control of a [[hypervisor]], instead of being in direct control of the hardware.

On mainframes IBM introduced the notion of a [[virtual machine]] in 1968 with [[CP/CMS]] on the [[IBM System/360 Model 67]], and extended this later in 1972 with [[VM (operating system)|Virtual Machine Facility/370]] (VM/370) on [[IBM System/370|System/370]].

On [[x86]]-based [[personal computer]]s, [[VMware]] popularized this technology with their 1999 product, [[VMware Workstation]],<ref>{{cite web
 | url         = http://www.vmware.com/company/mediaresource/milestones.html
 | title       = VMware company history
 | url-status  = dead
 | archive-url  = https://web.archive.org/web/20110416074213/https://www.vmware.com/company/mediaresource/milestones.html
 | archive-date = 2011-04-16}}</ref> and their 2001 VMware GSX Server and VMware ESX Server products.<ref>{{cite web
 | url   = http://news.cnet.com/2100-1001-242656.html
 | title = VMware ready to capitalize on hot server market
 | date  = June 30, 2000}}</ref> Later, a wide range of products from others, including [[Xen]], [[Kernel-based Virtual Machine|KVM]] and [[Hyper-V]] meant that by 2010 it was reported that more than 80 percent of enterprises had a virtualization program or project in place, and that 25 percent of all server workloads would be in a virtual machine.<ref>{{cite web |url=https://www.infoworld.com/article/2626340/gartner--1-in-4-server-workloads-will-be-virtual-by-year-end.html |title=Gartner: 1 in 4 server workloads will be virtual by year-end |date=September 27, 2010 |author=Jon Brodkin |work=Network World}}</ref>

Over time, the line between virtual machines, monitors, and operating systems was blurred:
* Hypervisors grew more complex, gaining their own application programming interface,<ref>{{cite web |url=https://www.vmware.com/support/developer/vix-api |title=VMware API |access-date=26 November 2008 | publisher=VMware |archive-url=https://web.archive.org/web/20081126065041/https://www.vmware.com/support/developer/vix-api/ |archive-date=26 November 2008 |url-status=dead}}</ref> memory management or file system.<ref>{{cite web | url=https://www.vmware.com/products/vi/esx/vmfs.html | title=VMware file system | access-date=26 November 2008 |archive-url=https://web.archive.org/web/20081126093742/https://www.vmware.com/products/vi/esx/vmfs.html |archive-date=26 November 2008 |url-status=dead}}</ref>
* Virtualization becomes a key feature of operating systems, as exemplified by [[Kernel-based Virtual Machine|KVM]] and [[LXC]] in Linux, [[Hyper-V]] in [[Windows Server 2008]] or [[HP Integrity Virtual Machines]] in [[HP-UX]].
* In some systems, such as [[POWER5]] and later POWER servers from IBM, the hypervisor is no longer optional.<ref>{{cite book | url=https://www.redbooks.ibm.com/abstracts/sg247940.html?Open | title=IBM PowerVM Virtualization Introduction and Configuration | date=30 September 2016 | access-date=5 June 2024}}</ref>
* Radically simplified operating systems, such as [[CoreOS]] have been designed to run only on virtual systems.<ref>{{cite web |url=https://www.zdnet.com/article/snappy-ubuntu-challenges-coreos-and-project-atomic-on-lightweight-cloud-servers/ |title=Snappy Ubuntu challenges CoreOS and Project Atomic on lightweight cloud servers |date=December 10, 2014 |author=Steven J. Vaughan-Nichols |website=[[ZDNET]]}}</ref>
* Applications have been re-designed to run directly on a virtual machine monitor.<ref>{{cite web | url=http://www.theserverside.com/news/thread.tss?thread_id=43424 | title=JRockit's Liquid VM could be the first real Java OS | access-date=26 November 2008}}</ref>

In many ways, virtual machine software today plays the role formerly held by the operating system, including managing the hardware resources (processor, memory, I/O devices), applying scheduling policies, or allowing system administrators to manage the system.