This page explains what happens to Informatics servers when the electricity goes off.
The School's servers are at three main sites, but the sites are not equally equipped for power failures.
Appleton Tower
There is an Uninterruptible Power Supply (UPS) system which covers the Appleton Tower main server room, and there is a backup generator - so we do not expect our servers in Appleton Tower to lose power unless there is a particularly long outage.
There is virtually no backup power provision for any other part of Appleton Tower, so power would be lost immediately in these areas.
College Server Room (JCMB, Kings Buildings)
There is a UPS system which covers the College server room, and there is a backup generator - so we do not expect our servers in JCMB to lose power, except in the case of a particularly long outage.
Informatics Forum
The Informatics Forum has one central UPS system which provides power to all of the basement server rooms, including both of the self-managed server rooms. This UPS is rated at 200 kVA and, if fully-loaded, its expected run-time on batteries (or 'autonomy') is about 30 minutes. However there is no backup generator.
30 minutes is not long enough to allow us to find out the expected duration of an outage and take the necessary action. If the outage is within normal working hours, computing staff will start to shut down servers immediately, based on criticality and use of power, to preserve power for essential machines for as long as possible.
Outside working hours, managed servers will shut themselves down automatically as the UPS batteries finally run down. Most will restart once power is restored. However, to preserve data integrity, some are set up to not restart automatically, and in these cases computing staff will restart them manually when it is safe to do so.
There is no UPS cover for the rest of the Informatics Forum: in the event of an external power outage, power to all offices (and all network equipment) will immediately be lost.
Further Information
Our network monitoring site has a link to UPS status information.