Power saving

The department's electricity bill is one of the largest single items of expenditure and as part of a campaign to reduce this we want to encourage everyone to adopt power saving practices with their IT equipment. Note that a single PC and monitor left on for a year adds £44 to our bill and there are several hundred desktop systems in the department. Here are some general rules.

  • If you are aware of a system with a monitor that appears to be constantly powered up then please bring it to the attention of the owner or the local IT support as appropriate.
  • It is recommended that all monitors and printers should have power saving enabled but if this is not possible then they should be turned off at night and at weekends.
  • Never switch off a system without considering the implications (see section 2 below).
  • If you manage your own system ensure that power saving is enabled wherever possible.

Monitors

Most monitors have a power saving mode which reduces the power consumption to about 10%. Systems should be setup to ensure that full advantage is taken of this facility. If any of your systems are not configured to automatically put the monitor into power save after a period of inactivity then please take some action. Please consult your local IT support staff if they manage your system or if you need some advice on how to set up your own machine. N.B. In some cases, running a screen saver will prevent the monitor from entering power saving mode so if in doubt please disable all screen savers.

If for any reason a system's monitor cannot be configured for power saving mode then please make sure the monitor is switched off at night and over weekends. (For example, some graphics cards do not support power saving when running Windows NT 4.)

Systems

N.B. Powering down a system can have unforeseen effects so if in doubt please consult your IT support staff for advice.

Most modern systems have power saving capabilities which should be used whenever possible. If this is not possible then consider powering down your system but only after considering the following.

Unix systems: These are almost invariably managed by IT staff or designated users in some larger groups. They should not be powered down by users. Consult IT staff if unsure.

User Managed Linux and Windows systems:

Where possible all systems should be switched off at the end of the working day. However, this may be a problem in some circumstances so please check the following.

  1. Is anyone else using the system via the network ? E.g. Interactive logins, batch jobs, file or print serving?
  2. Has the system been setup to store some files on the local disk that will be backed up outside of working hours e.g by central IT staff or the OUCS ADSM service (also known as HFS)?


    a) For ADSM backups to succeed the system must be left running throughout our allocated ADSM slot. Unfortunately, for desktop systems, this is currently Sunday night/Monday morning which necessitates leaving such systems on over the weekend. We have requested that OUCS move our slot to a weekday so that ADSM backed up systems can be switched off at weekends.


    b) If you have made arrangements to have your system backed up by Central Physics then you should leave your system permanently on as backups occur every night and weekend.

Centrally Managed Windows systems: In most circumstances these can be shut down every night. User files are stored on centralised servers rather than desktops and are backed up from there. If you have made special arrangements to have local data backed up centrally (e.g. for systems involved in running experiements) then the system should be always on.

Printers

Most modern printers support power saving so please ensure this is enabled. If your printer is incapable of power saving then it should be switched off at night and weekends unless it is in a shared public area.

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