Suitable storage devices and storage media
The choice of secondary storage medium depends on the use it is required for. When deciding on the type of device needed, a user should consider:
- Cost - what is the cost per gigabyte (GB)?
- Capacity - how much data can the medium hold?
- Speed of access - how quickly can data be transferred to and from the medium?
- Portability - how portable is the medium? Does it need to be portable?
- Durability - how robust is the medium, and how robust will it need to be?
- Reliability - how resilient and long-lasting is the medium?
Once these factors are taken into consideration, an appropriate choice can be made.
The advantages and disadvantages of different storage devices and storage media relating to characteristics
| Medium | Type | Capacity | Speed of access | Portability | Durability | Reliability | Typical use |
| Hard disk | Magnetic | 500 GB-12 TB | Slow | Internal devices are fixed. External hard disks are portable | Reasonable, but prone to damage if dropped or knocked | Generally very reliable if looked after | Long-term storage of programs and data |
| CD-ROM/R | Optical | 640 MB | Very slow | Very portable | Easily scratched, damaged or broken | Generally very reliable if looked after | Backups, archives, copies of data, distribution of programs and music |
| CD-RW | Optical | 640 MB | Very slow | Very portable | Easily scratched, damaged or broken | Generally very reliable if looked after | Copies of data, transferring files between computers |
| DVD-ROM/R | Optical | 4.7 GB | Slow | Very portable | Easily scratched, damaged or broken | Generally very reliable if looked after | Backups, copies of data, distribution of games, TV programmes and movies |
| DVD-RW | Optical | 4.7 GB | Slow | Very portable | Easily scratched, damaged or broken | Generally very reliable if looked after | Backups, archives, copies of data |
| Blu-ray-ROM/R | Optical | 50 GB | Slow | Very portable | Easily scratched, damaged or broken | Generally very reliable if looked after | Distribution of TV shows and movies |
| Blu-ray-RW | Optical | 50 GB | Slow | Very portable | Easily scratched, damaged or broken | Generally very reliable if looked after | Backups, archives |
| Solid-state drive | Flash memory | 256 GB-4 TB | Very fast | Internal devices are fixed. External hard disks are portable | Robust and resilient | Reliable | Long-term storage of programs and data where high performance is required |
| USB memory stick | Flash memory | 2 GB-2 TB | Fast | Very portable | Robust and resilient | Reliable | Copies of data, transferring files between computers |
| Medium | Hard disk |
|---|---|
| Type | Magnetic |
| Capacity | 500 GB-12 TB |
| Speed of access | Slow |
| Portability | Internal devices are fixed. External hard disks are portable |
| Durability | Reasonable, but prone to damage if dropped or knocked |
| Reliability | Generally very reliable if looked after |
| Typical use | Long-term storage of programs and data |
| Medium | CD-ROM/R |
|---|---|
| Type | Optical |
| Capacity | 640 MB |
| Speed of access | Very slow |
| Portability | Very portable |
| Durability | Easily scratched, damaged or broken |
| Reliability | Generally very reliable if looked after |
| Typical use | Backups, archives, copies of data, distribution of programs and music |
| Medium | CD-RW |
|---|---|
| Type | Optical |
| Capacity | 640 MB |
| Speed of access | Very slow |
| Portability | Very portable |
| Durability | Easily scratched, damaged or broken |
| Reliability | Generally very reliable if looked after |
| Typical use | Copies of data, transferring files between computers |
| Medium | DVD-ROM/R |
|---|---|
| Type | Optical |
| Capacity | 4.7 GB |
| Speed of access | Slow |
| Portability | Very portable |
| Durability | Easily scratched, damaged or broken |
| Reliability | Generally very reliable if looked after |
| Typical use | Backups, copies of data, distribution of games, TV programmes and movies |
| Medium | DVD-RW |
|---|---|
| Type | Optical |
| Capacity | 4.7 GB |
| Speed of access | Slow |
| Portability | Very portable |
| Durability | Easily scratched, damaged or broken |
| Reliability | Generally very reliable if looked after |
| Typical use | Backups, archives, copies of data |
| Medium | Blu-ray-ROM/R |
|---|---|
| Type | Optical |
| Capacity | 50 GB |
| Speed of access | Slow |
| Portability | Very portable |
| Durability | Easily scratched, damaged or broken |
| Reliability | Generally very reliable if looked after |
| Typical use | Distribution of TV shows and movies |
| Medium | Blu-ray-RW |
|---|---|
| Type | Optical |
| Capacity | 50 GB |
| Speed of access | Slow |
| Portability | Very portable |
| Durability | Easily scratched, damaged or broken |
| Reliability | Generally very reliable if looked after |
| Typical use | Backups, archives |
| Medium | Solid-state drive |
|---|---|
| Type | Flash memory |
| Capacity | 256 GB-4 TB |
| Speed of access | Very fast |
| Portability | Internal devices are fixed. External hard disks are portable |
| Durability | Robust and resilient |
| Reliability | Reliable |
| Typical use | Long-term storage of programs and data where high performance is required |
| Medium | USB memory stick |
|---|---|
| Type | Flash memory |
| Capacity | 2 GB-2 TB |
| Speed of access | Fast |
| Portability | Very portable |
| Durability | Robust and resilient |
| Reliability | Reliable |
| Typical use | Copies of data, transferring files between computers |
In many situations, more than one type of Non-volatile memory external to the CPU and used for long-term storage of programs and data. may be suitable. For example, a USB stick or a CD-RW may be used to transfer files, or to back up data.
Image caption, Hard disk
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