Reliability in computer systems questions and answers
Q1. Explain why users need to be able to rely on computers working.
A1. Users might stop using the equipment for good. They might get very stressed out and frustrated over time. They might decide never to buy a product from that computer manufacturer again. Makers of computers might go out of business if enough people felt the same way. Users might change their habits.
Q2. Describe the term ‘failover’.
A2. Providing a second identical piece of equipment that can automatically take over if the first piece of equipment fails.
Q3. Describe an example of using ‘failover’ on a network.
A3. For example, a key piece of equipment on a network is the server. This controls the whole network and if it fails, the whole network will not be available for anyone to use. By providing a second server that will start automatically and is up-to-date with everyone's files, you can ensure that the network will carry on as if nothing has happened if the first server breaks down.
Q4. What does the word 'reliable' mean?
A4. Something that is reliable means you can depend on it.
Q5. What is a server?
A5. A server is just a computer, except it usually has a lot of RAM and hard drive space, because it has to store everyone's files and work with lots of computers at the same time. It will also have a Network Operating System loaded up on to it, to control security and communications around the network.
Q6. On a network, what is meant by a 'client'?
A6. A client is jargon for a computer on a network. It is served by the server so it is called a client.
Q7. Hard drives will always fail one day. Why?
A7. Hard drives are mechanical devices with moving parts. These will wear out over time and can be damaged by dust. They can also be damaged by environmental factors such as heat in a hot server room.
Q8. What is meant by a 'back-up' of data?
A8. A back-up ais a second copy of something, used in case the main copy fails or is destroyed.
Q9. Companies often say that data is the most valuable part of their business, even more so than the people who work there. Explain this statement.
A9. People can be replaced. Data is irreplacable. If a company doesn't back-up data and they e.g. had a fire or a system malfunction, they could lose all their data - all their product information, their employee information, details about customers, who ows them money, their accounts, future projects and so on.
Q10. Lots of companies now back up their data to the 'cloud'. Use the Internet. What is the cloud and what are the advantages of storing data to the cloud rather than on a hard drive or tape?
A10. The cloud simply means storing your data off-site with a third part company e.g. SkyDrive, GoogleDrive, Dropbox. They take responsibility for storing your data securely, for ensuring that it is protected from viruses, stored in more than one place and different versions are stored securely. Network Managers can automate their cloud back-ups to ensure they are done properly and on time. A hard drive or tape has to be loaded into a machine by someone and they have to be rotated using perhaps seven different tapes, one for each day of the week. They have to be unloaded and physically taken off site, where they may get damaged or stolen.