Institutional computers are often left on for the following reasons:
- To allow a backup service to copy files overnight
- To preserve the 'desktop context' overnight e.g. leave applications such as Word, Firefox and email open
- To allow software updates or 'patches' to be installed
- To allow users to access their computer remotely e.g. to retrieve a file while at a conference
- To avoid waiting for computer to start up or boot
- To allow a desktop computer to act as a web server or file store
- To "keep-alive" another computer
- To constantly filter emails so that web-based email messages are organised and more easy to use
- To allow distributed modelling projects to use desktop computers e.g. SETI, climateprediction.net and GRID experiments in general
- Standby (S3) and hibernate (S4) power saving modes cannot be implemented reliably or without disrupting other services
This often means that desktop computers are often on without doing 'useful' work. This section of the Low Carbon ICT wiki describe tools and practices for reducing the amount of time that desktop computers are on and wasting energy.
Contents
Tools and practices
Waking computers remotely
A wake-on-LAN (WoL) service allows people to switch a computer on without having to be physically in the same location. By providing a facility that can be used to switch computers on 'remotely' it becomes possible to safely switch computers into low power states more often. For instance, many organisations will ask staff to leave computers on to allow backup and software patching services to access their computers. If computers can be switched on by these backup and patching services, users can switch their machines off without disrupting this essential activity.
Case study: University of Oxford's WoL infrastructure
The University of Oxford wake-on-LAN infrastructure enables ICT managers, end-users and managers of third-party services to wake computers remotely. The WoL service is being used so that members of the University can be asked to switch their computers to low power states (off, standby or hibernate) when they are not in use.
Configuring computers to move into low power states automatically
Desktop computers have four main power states: On (S0) Sleep or standby (S3) Hibernate (S4) Off (S5). Most computing devices are built to be able to detect when they are not being used. There are however a number of issues associated with the way that power saving capabilities have been implemented:
Test cases: The purpose of this document is to describe a way to gather structured test-case data about implementing power management on desktop computers
- Can you configure computer to automatically go into S3 or S4 mode automatically?
- Does computer drop to S3 and S4 after pre-configured time unit?
- Does computer stay in S3 and S4 if you do not switch it back on e.g. using WoL, pressing power button, moving mouse/ pressing a key?
Changing BIOS configurations so that computer can be woken by wake-on-LAN "magic packets"
Not all computers can be woken by wake-on-LAN "magic packets". BIOS settings can be changed by pressing a function key (e.g. F8) when a computer boots but this is not convenient if many computers need to be changed. BIOS settings can be changed centrally by...
Allowing end-users to configure power management
Case study: Configuring computers to move into standby automatically at Liverpool University
Asking users to switch their computers off
Case study: Asking users to switch their computers off at the University of Oxford Case study: Asking users to switch their computers off at the University of Leeds
Turning computers off if nobody is logged in
http://pcwww.liv.ac.uk/powerdown/
Turning computers off if nobody is logged in using Altiris
Use Altiris to schedule shutdown tasks by running a job on (all) PCs at intervals through the night to run the shutdown command, if no user is logged in.
Switch computers in clusters on as needed
Switching computers on automatically at pre-configured time
Computers can be woken remotely at a pre-configured time, for instance by a WoL service. This can help where computers are particularly slow to boot from off. Doing this presents the problem that computers may be switched on when they are not needed. This is less of a problem if this policy is coupled with automatically putting computers into S3 mode, or turning them off. People wishing to put computers to sleep (S3) after they have been woken should test to make sure this approach is reliable (some computers may not enter or stay in S3 mode, and consume the same number of Watts as they do when on).
Other tricks
Disabling screen savers
If computers cannot be switched off they could be offered by default for GRID experiments
Preserving state of desktop before switched off
- New version of firefox can do this if configured
Commercial solutions
Life-cycle considerations
The manufacture and transport of computing equipment results in a considerable amount of CO2 to be released into the atmosphere, many of the components are considered toxic waste and have to be carefully recycled, and the manufacture of circuit components requires large volumes of clean water. With this in mind it becomes obvious that for any organisation to truly improve its environmental performance it will have to carefully control its procurement processes.
Extend the life-cycle
Buy equipment that will perform useful work for the longest period of time. Notes: warranty, system maintenance to improve performance.
Promote greater sharing of resources
Organisations can reduce their carbon footprint by buying fewer devices and asking people to share equipment more often.