Sleep mode
Encyclopedia
Sleep mode refers to a low power mode for electronic devices such as computers, televisions, and remote controlled devices. These modes save significant electrical consumption compared to leaving a device fully on and idle, but allow the user to avoid having to reset programming codes or wait for a machine to reboot
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...

. Many devices signify this power mode by a pulsing LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

 power light.

Sleep

Sleep mode can go by many different names, including Stand By (for Microsoft Windows 98-Server 2003), Sleep (for Mac OS 8
Mac OS 8
Mac OS 8 is an operating system that was released by Apple Computer on July 26, 1997. It represented the largest overhaul of the Mac OS since the release of System 7, some six years previously. It puts more emphasis on color than previous operating systems...

-Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

, Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

, Windows 7, Windows Server 2008), and Suspend (Windows 95
Windows 95
Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft, and was a significant progression from the company's previous Windows products...

, Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

). When placed in this sleep mode, aside from the RAM
Random-access memory
Random access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in...

, which is required to restore the machine's state, the computer attempts to cut power to all unneeded parts of the machine. Because of the large power savings, most laptops automatically enter this mode when the computer is running on batteries and the lid is closed.

A computer must consume some power while sleeping to run the circuits required to recognise and act on a wake-up event; a sleeping computer is a case of a device consuming standby power
Standby power
Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity , refers to the electric power consumed by electronic and electrical appliances while they are switched off Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity...

, covered by regulations in many countries limiting such power under the One Watt Initiative
One Watt Initiative
The One Watt Initiative is an energy-saving initiative by the International Energy Agency to reduce standby power-use by any appliance to not more than one watt in 2010, and 0.5 watts in 2013, which has given rise to regulations in many countries and regions.-Standby power:Standby power,...

 to one watt from 2010.

Hibernation

Hibernation is functionality allowing a computer to be turned off completely while maintaining its state. On switching back on the state is restored to the way it was, with files open, unsaved data intact, etc.

Hybrid sleep

Sleep mode and hibernation can be combined: the contents of RAM are first copied to non-volatile storage like for regular hibernation, but then, instead of powering down, the computer enters sleep mode. This approach combines the benefits of sleep mode and hibernation: The machine can resume instantaneously, but it can also be powered down completely (e.g. due to loss of power) without loss of data, because it is already effectively in a state of hibernation. This mode is called "hybrid sleep" in Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

.

A hybrid mode is supported by some portable Apple Macintosh computers, compatible hardware running Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

 and 7, and some specially configured Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 machines.

ACPI

ACPI
Advanced Configuration and Power Interface
In computing, the Advanced Configuration and Power Interface specification provides an open standard for device configuration and power management by the operating system....

 is the current standard for power management
Power management
Power management is a feature of some electrical appliances, especially copiers, computers and computer peripherals such as monitors and printers, that turns off the power or switches the system to a low-power state when inactive. In computing this is known as PC power management and is built...

, superseding APM
Advanced Power Management
Advanced power management is an API developed by Intel and Microsoft and released in 1992 which enables an operating system running an IBM-compatible personal computer to work with the BIOS to achieve power management.Revision 1.2 was the last version of the APM specification, released in 1996....

 and providing the backbone for sleep and hibernation
Hibernate (OS feature)
Hibernation in computing is powering down a computer while retaining its state.Upon hibernation, the computer saves the contents of its random access memory to a hard disk or other non-volatile storage...

 on modern computers. Sleep mode corresponds to ACPI mode S3. When a non-ACPI device is plugged in, Windows will sometimes disable stand-by functionality for the whole operating system. Without ACPI functionality, as seen on older hardware, sleep mode is usually restricted to turning off the monitor and spinning down the hard drive.

Reliability

When sleep mode was first introduced it was usually not tested as thoroughly as the normal mode, causing various problems especially with peripherals such as computer mice. Partly for these reasons, in a working environment sleep mode was generally avoided because the costs associated with wasted time and materials far outweighed the savings in energy from sleep mode.

Microsoft Windows

Microsoft Windows 2000 and later support sleep at the operating system level (OS-controlled ACPI S4 sleep state) without special drivers from the hardware manufacturer. Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

's Fast Sleep and Resume feature saves the contents of volatile memory to hard disk before entering sleep mode. If power to memory is lost, it will use the hard disk to wake up. The user has the option of hibernating directly if they wish.

Sleep mode is often under-used in business environments as it is difficult to enable post-deployment without resorting to third-party PC power management
PC power management
PC power management refers to the mechanism for controlling the power use of personal computer hardware. This is typically through the use of software that puts the hardware into the lowest power demand state available...

 software This omission by Microsoft has been criticized as having led to a huge waste in energy.

There is a significant market in third-party PC power management
PC power management
PC power management refers to the mechanism for controlling the power use of personal computer hardware. This is typically through the use of software that puts the hardware into the lowest power demand state available...

 software offering features beyond those present in the Windows operating system. available. Most products offer Active Directory
Active Directory
Active Directory is a directory service created by Microsoft for Windows domain networks. It is included in most Windows Server operating systems. Server computers on which Active Directory is running are called domain controllers....

 integration and per-user/per-machine settings with the more advanced offering multiple power plans, scheduled power plans, anti-insomnia features and enterprise power usage reporting. Notable vendors include 1E
1E
1E is a privately owned software company based in the United Kingdom. 1E has offices in London, New York, Frankfurt, Paris, and Noida. The company develops automated software solutions to address complexity, management costs and power consumption...

 NightWatchman., Data Synergy PowerMAN (Software)
PowerMAN (Software)
PowerMAN is a computer software program that allows PC power management to be centrally monitored and managed. The software allows an enterprise-wide power management strategy to be implemented. The product is used by many public sector organisations in both the US and UK. It is also used by...

 and Verdiem
Verdiem
Verdiem is a software corporation based in Seattle, WA. The company is privately owned and backed by venture capital. . Verdiem produces the Surveyor enterprise-class PC power management software and the free Edison home-use solution. The company has OEM agreements with Hewlett-Packard and Cisco...

 SURVEYOR

See also

  • Advanced Configuration and Power Interface
    Advanced Configuration and Power Interface
    In computing, the Advanced Configuration and Power Interface specification provides an open standard for device configuration and power management by the operating system....

  • Green computing
    Green computing
    Green computing or green IT, refers to environmentally sustainable computing or IT. In the article Harnessing Green IT: Principles and Practices, San Murugesan defines the field of green computing as "the study and practice of designing, manufacturing, using, and disposing of computers, servers,...

  • Hibernation (computing)
  • One Watt Initiative
    One Watt Initiative
    The One Watt Initiative is an energy-saving initiative by the International Energy Agency to reduce standby power-use by any appliance to not more than one watt in 2010, and 0.5 watts in 2013, which has given rise to regulations in many countries and regions.-Standby power:Standby power,...

  • PC power management
    PC power management
    PC power management refers to the mechanism for controlling the power use of personal computer hardware. This is typically through the use of software that puts the hardware into the lowest power demand state available...

  • Standby power
    Standby power
    Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity , refers to the electric power consumed by electronic and electrical appliances while they are switched off Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity...

  • Shutdown (computing)
    Shutdown (computing)
    To shut down or power off a computer is to remove power from a computer's main components in a controlled way. After a computer is shut down, main components such as CPUs, RAM modules and hard disk drives are powered down, although some internal components, such as an internal clock, may retain...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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