Secondary Storage
Magnetic, Optical, Solid State/Flash
Secondary Storage
Magnetic Storage
This is the oldest out the 3 and is used in Floppy disks, hard disks and tapes. It is very cheap and stores a lot of data. Magnetic disks read and write data by using a moving head inside the disk drive. Moving parts make this sort of storage quite slow to read/write. And more often than not these moving parts break. Magnetic media are also vulnerable to damage as well. Magnetic disks can be easily wiped by using a magnet, so they aren't very safe. Cost: 72GB Tape = £10 Maximum Capacity: Up to 1TB Access Speed: Slow because the tape drive has to read through the tape. Portability: They are compact but require a tape drive to use. Durability:Limited, wears out with repeated use. If used once for archiving they can last 15 years. They are affected by heat and magnetic fields. Reliability: Very reliable if not damage. Typical Use: Good for back-ups and archiving, but too slow for general use.
Optical Storage
Optical media is where lasers write data to the disc and read data from it. Optical Media includes CD's and DVD's. Cost:50*4.7GB DVD-R for £15 (30p each). Capacity: CD: 640MB DVD: 4-17GB Access Speed: CD: Up to 7.6MB/s DVD: 16MB/s Portability: Easy to carry in a large pocket or bag. Durability: CD: 20-100 years DVD: 2-15 years Reliability; Good for medium usage but degrades over time. Typical Use: CD-ROM, CD-R, CD-RW, Backup/Archive where higher capacity is needed.
Solid State/Flash Storage
Flash memory is very fast at read/writing due to the fact it doesn't have any moving parts. Flash memory isn't as fast as RAM. Also less can go wrong with your data compared to hard disks and magnetcic storage. The following data is about USB memory sticks only. Cost:32GB for £45 64GB for £120 Capacity:64MB to 64GB Access speed: 480Mb/s (speed of USB 2) Portability: Very small, can put in any pocket or even on a key-ring. Durability: Very durable, some memory sticks can survive going into a washing machine however some can be snapped quite easily. Reliability: Very reliable but can corrupt files if removed during saving or too early. Typical use: Personal use, moving files between computers.