Storage Devices and Media
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- Advantages: Large storage capacity for a low price; well-established and reliable technology.
- Disadvantages: Contains moving parts, which can fail if dropped or knocked; slower access speeds compared with solid-state storage; consumes more power and generates more heat.
- Advantages: Cheap to produce in large quantities; portable and easy to distribute; not affected by magnetic fields.
- Disadvantages: Can be scratched or damaged relatively easily; slower data transfer speeds than solid-state storage; being replaced by online and solid-state alternatives in many uses.
- Advantages: Much faster read and write speeds than magnetic storage; more resistant to physical shock since there are no moving parts; smaller, lighter, and uses less power.
- Disadvantages: More expensive per gigabyte than magnetic storage, although prices continue to fall; a limited number of write cycles before the memory degrades.
- Advantages: Files can be accessed from anywhere with an internet connection; provides automatic off-site backup in case of local device failure; makes collaboration and file sharing straightforward.
- Disadvantages: Requires a reliable internet connection to access files; raises concerns about data security and privacy since files are stored on a third party's servers; ongoing subscription costs for large amounts of storage.
- Storage device: hardware that reads and writes data to a storage medium.
- Storage medium: the physical material on which data is recorded.
- Solid-state storage: storage with no moving parts that stores data electronically.
- Cloud storage: storage of data on remote servers accessed via the internet.
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Introduction to Storage
Storage devices and storage media are used to hold data, programs, and files so that they can be retrieved and used again in the future, even after the computer has been switched off. This is different from the computer's main memory (RAM), which loses its contents when the power is removed. Storage is essential because computers need somewhere permanent to keep the operating system, application software, and user-created files such as documents, photographs, and videos.
A storage device is the piece of hardware that reads and writes data, such as a hard disk drive, while the storage medium is the physical material on which the data is actually recorded, such as the magnetic disk inside the drive. Storage technologies are commonly grouped into magnetic, optical, and solid-state categories.
Magnetic Storage
Magnetic storage devices record data by magnetising tiny areas on a surface coated with magnetic material. The most common example is the hard disk drive (HDD), which consists of one or more spinning metal platters read and written to by a moving head. Hard disk drives are widely used as the main internal storage in desktop and laptop computers because they offer large storage capacities at a relatively low cost per gigabyte.
Optical Storage
Optical storage devices use a laser to read and write data as tiny pits and lands on the surface of a disc. Common examples include CDs (Compact Discs), DVDs (Digital Versatile Discs), and Blu-ray discs, which offer increasing amounts of storage capacity in that order. Optical discs are often used for distributing software, music, and films, and for creating backup copies of data.
Solid-State Storage
Solid-state storage devices, such as Solid State Drives (SSDs) and USB flash memory drives, store data electronically in flash memory chips with no moving parts. Solid-state storage has become increasingly popular in laptops, smartphones, and tablets because of its speed and durability.
Memory Cards
Memory cards, such as SD (Secure Digital) cards and microSD cards, are a compact form of solid-state storage widely used in digital cameras, smartphones, and other portable devices where space is limited. They allow storage to be easily removed and transferred between compatible devices.
Cloud Storage
Cloud storage allows data to be saved on remote servers accessed over the internet, rather than on a local device. Services that provide cloud storage allow users to access their files from any device with an internet connection and to share files easily with other people.
Choosing the Right Storage
The best storage choice depends on factors including the amount of data to be stored, how quickly it needs to be accessed, whether it needs to be portable, and how much the user is willing to spend. A photographer transferring images from a camera may use a memory card, a business backing up important records may use cloud storage for extra security, and a gaming computer may use a solid-state drive for fast loading times.
Key Terms to Remember
Backup and Archiving Considerations
Choosing a storage medium is closely linked to how an organisation plans to back up and archive its data. A backup is a copy of data kept in case the original is lost or damaged, while archiving involves moving data that is no longer regularly used to cheaper, long-term storage. Many organisations follow a rule of keeping backup copies in more than one physical location, and increasingly on more than one type of medium, so that a single disaster such as a fire or theft cannot destroy every copy of important data at once.
Magnetic tape, although now rarely used for everyday storage, is still used by some large organisations for long-term archiving because it is inexpensive per gigabyte and can reliably store huge volumes of data that do not need to be accessed frequently.
Storage Capacity and Units
Storage capacity is measured in units based on the byte, with each unit roughly one thousand times larger than the one before it: kilobyte (KB), megabyte (MB), gigabyte (GB), and terabyte (TB). Understanding these units helps when comparing the capacity of different storage devices, for example a typical USB flash drive might hold between 16GB and 256GB, whereas a modern hard disk drive used in a desktop computer might hold several terabytes.
Network-Attached Storage
Network-Attached Storage (NAS) is a dedicated storage device connected to a network, allowing multiple computers and users to access the same shared files and folders. Small businesses and schools often use NAS devices so that staff and students can save and retrieve files from a central location rather than storing important data separately on individual computers, which also makes backing up data far more straightforward since only one device needs to be backed up.
Redundant Array of Independent Disks (RAID)
Some organisations use several hard disk drives together in an arrangement known as RAID (Redundant Array of Independent Disks) to improve either performance, reliability, or both. In a mirrored RAID setup, the same data is written to two disks simultaneously, so that if one disk fails the other still holds a complete, unaffected copy of the data, which is especially valuable for servers that must remain available at all times.
Selecting Storage for Portable Devices
Smartphones and tablets typically use built-in solid-state flash memory rather than a hard disk drive, since solid-state storage is smaller, lighter, more energy-efficient, and far more resistant to the everyday knocks and vibrations these portable devices experience. This is a good example of how the physical constraints and expected use of a device directly influence which storage technology is the most sensible choice.
Summary
Storage devices and media allow data to be kept permanently, unlike the temporary contents of main memory. Magnetic storage such as hard disks offers large, affordable capacity; optical storage such as DVDs is useful for distribution; solid-state storage such as SSDs and memory cards offers speed and durability; and cloud storage provides flexible, remote access. The right choice depends on the balance between cost, speed, capacity, and portability needed for a particular task.
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