3.1 Storage devices and media

Storage devices and media

In this session you will look at many  different storage devices and the media that is used today and well as there use, the capacity and there advantage and disadvantage.

The difference between storage devices and media

A storage device is something that has the ability to read and also write information to and from storage media, for example a CD/DVD writer or tape drive.

Storage devices and media: their advantages and disadvantages
Storage devices Advantage Disadvantage
Fixed hard disk: found in most of the computers as the main storage device.
  • Their capacity is constantly increasing as prices are decreasing.
  • Fast access
  •  Very difficult to fix.
  • Limited life span.
  • Very slow to access.
Portable hard disk drives: a portable version of the hard disk. Ideal for transferring data from one computer to another and also used to increase a system’s storage capacity.
  •  They can often be powered using the connecting USB cable.
  • Add extra storage capacity to the computer.
  •  Similar to larger hard disk; difficult to repair and a limited lifespan.
  • Capacity is not as large as standard hard disk.
   Magnetic tapes: used most commonly for large scale data storage and backup.
  •  A low cost way of storing hundred of gigabytes of data.
  • Information can be set to back up overnight or outside of office hours.
  •  A special drive is require to read and write data to them.
  • Slow to access.
  • Not really practically nowadays.
   Optical CD/DVD: optical disk,normally used in retail for music releases and films to be played on home entertainment systems.
  •  Large storage capacities.
  • Low cost due to mass production.
  • Long lifespan if stored carefully.
  •  Scratches can make them unreadable.
  • Information is read-only.
   CD/DVD-ROM: optical disk, used to store commercial computer software such as an encyclopedia, game or installation disk.
  •  Similar to that of CD/DVD disks.
  • Large software packages can be easily distributed.
  •  If damaged, software must usually be purchased again.
   CD/DVD-R(Media):optical disk that can be written with data or media files once only. Used for backups and writing music CD.
  •   Low cost production.
  • Longer lifespan.
  • Disk can be open and added to until they are fulled.
  • Error can occur during written.
  • Data cannot be erased.
   CD/DVD-RW: optical disk that can be written with computer or  media files, erased and used again.
  • Similar to that of CD/DVD-R disks.
  • Each part of the disk can be erased and rewritten to hundred of times.
  •  Disk may stop working due to repetitive erasing and rewriting.
  • Not all disk players can play re writable disks.
   DVD-RAM:similar to a DVD-R but designed to be more robust, with quicker access.
  •  Re writable and protected from damage.
  • Designed and manufactured to a higher standard.
  •  More expensive than standard optical  disks.
  • less compaible with household players.
   Blu-ray: a high capacity optical disk use for high definition movie and data backup.
  •  Able to store full length high definition films.
  • Up to 10 times the capacity or DVD disks.
  •  Commercial usage limited to films.
  • Blu-ray content more expensive than standard DVDs.
   Solid state memory: used microchips to store information with no moving parts; found in portable drives and memory cards.
  •  Less susceptible to shock and damage.
  • Silent
  • Faster read and write times than standard hard disks.
  •  Practically impossible to repair if damaged.
  • Low storage capacity.
  • Price per gigabyte of storage is higher than hard disks.
   Pen drives: extremely portable solid state memory storage devices; designed for personal use and are normally built to use USB sockets.
  •  Ideal for pocket and key-ring size devices.
  • USB sockets are found on the majority of computers.
  •  Similar to that of solid states drive.
  • Can be easily misplaced or lost.
   Flash memory cards (Media): use solid state memory and found in digital cameras, mobile phones and gaming devices.
  •  Thumbnail-sized cards becoming common place.
  • Cost-effective way of adding additional storage to devices such as mobile phones.
  •  Smaller micro-style cards are easy to lose.
  • Many different models each with slightly different connectors.

 

Describing Storage devices and media

Different devices access and use memory in different ways. The following terms may be referred to when describing storage devices and media.

Main or internal memory: Memory used be a computer system when processing or storing information. Random Access Memory(RAM) can be read and also written to while using programs. The more the RAM in the system the much faster it is. Read Only Memory(ROM) hold only a permanent data and cannot be changed.

Backing storage: Any type of data storage device apart from RAM or ROM. So the hard disk drive that is found in PCs also use permanent data storage even when it’s turn off.

Serial and Sequential: Data is stored in a sequential sequence so that information stored can only be access by scanning through the data to that point.

Direct/random access: Any piece of information stored on a random access device and can be access without having to scan through its whole content.

Connectivity: Many computers may use an internal drive to read storage media, but external devices can also be connected by USB, Firewire or Ethernet cable or by using Wi-Fi networking.

 

Storage capacity

Storage device or media Typical capacities (at the same time of publication)
CD* 700 megabytes (MB)
 DVD* 4.7 or 8.54 gigabytes (GB) (single or dual layer)
 DVD RAM* 4.7 or 9.4 GB (single or dual layer)
 Blu-ray* 25 or 50 GB (single or dual layer)
 Pen drive** 2-64 GB
Flash memory cards** 2-64 GB
Portable disk drive**  320 GB-4 TB
Solid state drive **  100-500 GB
 Hard disk drive** 1-4 TB
 Magnetic tape**  500 GB to 5 TB

 

File sizes

8 bits 1 byte
1024 bytes 1 kilobyte (KB)
1024 kilobytes 1 Megabyte (MB)
1024 Megabytes 1 Gigabyte (GB)
1024 Gigabytes 1 Terabyte (TB)