From Unofficial BOINC Wiki
An electronic device that contains a rotating element of one or more platters that can record information using magnetization of the material that coats the surfaces. Disk drives come in various capacities, interconnection methods, speeds and reliability.
The rotating element consists of platters of glass or aluminum which is coated with a material that can retain magnetic polarization and using this capability information is written to the surface under one of the recording heads. Typically there are 3 to 5 platters giving us the capacity to store information on 5 to 9 surfaces (one surface is usually reserved for "servo" information (one of the ways that the drive "knows" where its heads are located).
The speed of the disk drive is measured in RPM (Revolutions Per Minute) and seek time. Disk drives are connected to the computer system through one of the following interconnection technologies:
- Integrated Drive Electronics (IDE), some times called Advanced Technology Attachment (ATA)
- Small Computer System Interface (SCSI)
- Serial Advanced Technology Attachment (SATA)
- Hard Disk
- Hard Disk Drive
- Hard Drive