Secondary Storage
Magnetic, Optical and Solid state/Flash
Magnetic Storage
Old technology now, and slowly becoming more and more outdated. They are often cheap and can store a lot of data (high capacity). Magnetic disks are read with a moving head inside the disk drive and magnetic tapes are read by moving the tape past a read-write head. Because they use moving parts, they are very vulnerable to damage and can break if moved whilst in use. Also vulnerable to data loss, and a big enough magnet could wipe an entire hard drive, erasing all your data!
Magnetic Tape
Access Speed: Very slow, has to be read serially Cost: Very Cheap - £10 for 72Gb Portability: Very portable, but need a tape reader the other end. Durability: Fairly durable whilst not in use. If the hard drive is moved or dropped whilst in use though then it can be damaged. Also very vulnerable to heat and magnets Reliability: Very reliable Typical Use: Portable, or extra, storage for a PC. Often used for backing up data.
Portable Hard Drive
Access Speed: 480Mb/s Cost: Cheap(ish) - £80 for 1TB Portability: Not portable at all Durability: Wears out with use, about 15 year life span. Also very vulnerable to heat and magnets Reliability: Very reliable Typical Use: Backups, too slow for much else.
Internal Hard Drive
Access Speed: 3 Gb/S Cost: Cheap(ish) - £80 for 1TB Portability: Not portable at all Durability: Fairly durable whilst not in use. If the hard drive is moved or dropped whilst in use though then it can be damaged. Also very vulnerable to heat and magnets Reliability: Very reliable Typical Use: Inside a PC as secondary storage