Finding that people do not use "stand-by" and "hibernate" when going away from their PCs, for fear of disrupting running network connections and background computations, Microsoft Research India has developed power-saving technology that virtualizes enterprise desktops to a backend server before putting the desktops to sleep.
The technology, called "LiteGreen," is described by the Microsoft researchers as a system to save desktop energy by virtualizing the user's desktop computing environment as a virtual machine, and then migrating it between the user's physical desktop and a virtual machine server, depending on whether the desktop computing environment is in use or idle.
Desktop computers are idle for a lot of time, because users are not constantly using the computer, and are frequently away for short intervals, said Venkat Padmanabhan, principal researcher at Microsoft Research India. A study at the Microsoft lab, for example, revealed that computers at the lab are idle for about 70 to 80 percent of the time.
It is not the case that energy is consumed by a PC in proportion to its use, said Ramachandran Ramjee, another principal researcher at the lab. It will consume energy even when it is not in use.
Users are however reluctant to put their PCs to sleep when they are away from their desks for a coffee break or a meeting, because that would break long-running network connections such as log-in sessions, IM presence and file sharing, or background computations such as the syncing and automatic filing of new mails, according to the researchers. In some cases, users also want to keep their machines reachable remotely, Ramjee said.
Using virtualization, LiteGreen allows a machine to be put to sleep, and save energy, without causing any disruption to the user, the researchers said.
The user's desktop computing environment is virtualized by encapsulating it in a virtual machine which is migrated between the physical desktop and a backend virtual machine server, depending on whether the desktop is being actively used or idle. The idle virtual machines will continue to run on the server, without disrupting the network connectivity or other background compute activities like downloads, Padmanabhan said.
The idle virtual machines on the server can also be used by the IS department to do system maintenance, and system upgrades and patches. The changes to the server image will then get synchronized to the desktop when it is brought out of sleep mode.
When a user returns to a machine that has been put to sleep, the machine is woken up from sleep, and the user is able to access in about 10 seconds his desktop environment through a remote desktop connection to the desktop virtual machine running on the virtual machine server. The desktop virtual machine is subsequently migrated back to the user's physical desktop machine without the user even noticing, in about one minute in a typical LAN environment, Ramjee said.
The technology is already deployed at Microsoft Research India with some 12 users testing it. It can be scaled to a wide-area network and the virtual machine server hosted in a cloud, provided there exists enough bandwidth to enable the quick movement of the virtual machines between the desktops and the server, Padmanabhan said.
Microsoft Research India is now working on the compression algorithms and redundancy elimination that will enable the virtual machines to be transferred to and from the back-end server more quickly.
The lab declined to comment on the commercialization of the technology, as its focus is on research, rather than business decisions.
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