Term
Describe some of the problems of not being able to use computers |
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Definition
| We are becoming increasingly dependent on computer systems at school, at work and at home.Consider what problems you would have if all of these computers stopped working! If the games console didn’t work you might be upset but it wouldn’t be a big problem. If the network at school went down you wouldn’t be able to get to any of the resources and teachers wouldn’t be able to show you their slides or use smart‐whiteboards. If there are problems with computers systems in shops they can’t sell anything and if bank systems have problems people cannot access their money, or worse still, other people can! |
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Term
Give an example of why reliability of computer systems is so important. |
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Definition
If computer‐controlled signage on motorways goes wrong there could be health and safetyimplications. If computer systems in hospitals go wrong people could die.
Look back at the case study we looked at about the London Ambulance System. |
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Term
How do you know how reliable a computer system is?
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Definition
| We talk about system availability meaning how long is available for. For example, if a system is down (unavailable) for 1 hour in a 100 hour period, then the system availability is 99% for this period. Normally equipment manufacturers will quote average availability over a long period of time. Another way of measuring a system’s reliability is to measure the length of time between system failures. MTBF is the Mean Time Between Failure and is quoted by equipment manufacturers as an indication of reliability. |
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Term
How do we protect against system failures? |
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Definition
Hardware Redundancy -
is one way to protect systems. This means having more than one of a critical component. For example, the computers in a commercial aeroplane will all have backup computers to take their place if they go wrong. |
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Term
What are Disaster Recovery Plans? |
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Definition
A computer system failure could mean that a company goes out of business in just a few days, disaster recovery plans are sometimes put in place so a company can switch over to a complete, new system, with all their own data on it, often within hours.
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