Storage Devices

13 min readOct 17, 2021

Storage device is any computer hardware that is used as storing and extracting data of a computer. Storage devices can store data and information both temporarily and permanently. That may be an internal or external to the computer. They store virtually any data on a computer through separate ROM (Read only memory).

Usage of Storage devices

The storage device is used for storing, porting, or extracting data and information from the computer. They can used for moving data one place to another place. It is used to temporarily store data when needed while inputting and processing data to storage devices. And they provide one of the core functions of the modern computers. And users can retrieve stored data and information anytime when they needed.

Types of storage

There are four types of storage devices in a computer. These are categorized according to the data retention time. Access time also effects categorization. They can be identified differently.

Primary storage

Primary storage devices are a medium that holds memory for short times or periods of time while the computer is running. As well as it has a much lower access time and faster performance. It also about two types of magnitude more regularly than secondary storage. RAM (Random Access Memory) and cache memory both are examples for primary storage devices.

The other main difference from other storage devices is that can direct access to CPU anytime. As well as primary storage is volatile and non — removable. The main storage devices found under primary storage are RAM and Cache memory.

Random Access Memory (RAM) — Main memory

The ram is located on the motherboard near to the CPU as a separate unit. The function of the RAM is to temporarily store the data to be processed and the instructions as well as the information processed. This memory can be divided into two main parts.

Dynamic RAM — DRAM

Made by capacitors. Should be constantly refreshed as well. Memory density increases and speed decreases relatively. As well as price is lower than SRAM.

Static RAM — SRAM

Made by logic gates. Memory density is lower than DRAM. But more expensive because of the access speed. Should not constantly refreshed.

Cache memory

The main task of the cache memory is temporarily stored frequently used data and instructions for quick processing. As the level of these memories increase, the memory capacity increases, and the speed decreases relative to it. [1]

Secondary storage

A secondary storage device is any non — volatile storage device that is on internally or externally connected to the computer. It can be any storage device around the primary storage that can be permanently storage data. Secondary storage device also calls as external storage device, auxiliary storage device, or backup storage device. Secondary storage always allow the user to permanently store data on them. [1]

secondary storage devices can be divided as the follows.

secondary storage devices can be divided as the above

Typically, secondary storage devices allow for the storage of data ranging from a few megabytes to petabytes. These devices are store virtually all programs, data, and applications stored on a computer, including the operating system, drivers, applications, and general user data. Hard disk drives, flash drives, USB drives, DVD drives, SD cards are examples for secondary storages. here are some of the key components of secondary storage.

Hard Disk Drive — HDD

HDD is a secondary storage device that is large enough to be permanently mounted on the system unit. HDD is data storage device that stores and retrieve digital data by using magnetic storage. As well as use as the main storage device in the computer. This is a non-volatile memory that controls the positioning, reading, and writing in the HDD which use to data storage. [1]

Tertiary storage

Tertiary storage is high-capacity data archives builds to incorporate huge number of removable media. Such as magnetic tapes or optical disks. Those are usually very slow than other storage devices. As well as a level below to the secondary storage devices. It allows to robotic mechanism which will mount and unmounted removable mass media into storage devices. The removable data are normally not stored in suitable drives but held in specially arranged retention slots, shelves, or carousels in an offline state in computer. As well as data are often copied into secondary storage before to use. [4]

Examples:

Magnetic tapes

Included a magnetically coated strips of plastic on which data can be encoded. Low expensive and slower than the other storage devices.

Optical disks

That storage holds digital data and information in digital format. And read those contents are using a laser by reader.

Offline storage

Offline storage refers to any storage medium that should be physically inserted into a system. Every time a user’s wants to access or edit data to offline storage s. Those are well known as external storage devices that can be easily plug, use, and remove. Data will be store permanently in offline storage. Offline storage is non-volatile memory. So, if the offline device unplugged or remove from the computer data will be stored permanently. And also, those storage devices are portable and can be used on any different operating system accurately.

Examples:

§ Compact discs

§ USB Drives

§ Floppy discs

§ External hard drives

Storage devices are the lack of computer hardware used to store data what is user want. And a hardware that is capable of holding data and information temporarily or permanently. Those storage devices can be divided as four parts.

Types of computer storage devices

Magnetic storage devices

A computer needs to store data and information in digital format. One of the techniques used to archive that purpose is magnetic storage devices. This device allows any data type of data storage using the technique magnetic medium. Digital data contain of binary information that consist of ones and zero. Magnetic storage is a non-volatile storage. Those are mostly used because it is relatively cheap compare with the other storage technologies. there are the many different types of magnetic storage devices bellow. [3] mentions some main types of them.

Hard Disk Drive (HDD)

hard disk drive is well known as hard drive. Hard drive is a storage device that can store all data to the computer from user in magnetic technique as physically. HDD is a secondary storage device that have huge capability of storage.It is capable to store more data than 500 GB. HDD contains One or more than disks. The disks are all mounted on the same axis and are coated with a very thin layer of metal oxide. HDD data stores by sub-orientation of the metal oxide layer by using the header

Floppy disk

Floppy disk is introduced by IBM company in 1969. Floppy disk also a media that store data usually used in personal computers. In this device was internally used iron oxide coat for storing data in magnetic method just equal to hard disk. Nowadays those are completely obsoleted.

Magnetic tape

Basically, magnetic tapes were used to recording voices and store them accurately. The magnetic tape technology was completely obsolete now. And now it replaced by CD (Compact disks) and DVDs. Magnetic tapes also used magnetic storage mechanism.

Optical storage devices

optical storage devices also a method of storage that is allows any read or write activities those are performed by using laser beam technology. This technology stores all the information in a optical disk. It calls optical memory. That is very useful for huge data storage ability. There are so many advantages of optical storages. Those are very cheap than the others, light weight, and easy to move. In optical storages, all data save as a dot pattern. And it can be read easily using the laser light. Data is read by laser beam while bouncing on the surface of storage medium. The laser beam makes dots while reading process. But it cost huge power to make that process. That process called as Burning data into the disc.

There are many different types of optical storage devices. Those are briefly described below.

CD ROM

CD Rom is made for the compact disc data readings. CD ROM allows to read compact disc read only memory and random-access category devices. It has a storage capacity of 800 MB. CD ROM use a low power laser beam to read data on compact disc. This is an evolution of the floppy disk. This is also becoming obsolete due to USB technology. [4]

DVD — ROM

DVD ROM also a read only memory that allows to read data from the disk. Extension of DVD is Digital Versatile Disk — Read Only Memory. And also, this belongs to the category of random-access devices. Normal DVD drive can store data up to 4.7 GB, but double layer DVD have capability of double data store than normal DVD. These are commonly used to store high quality data such as movies, video clips.

Blue Ray

Blue ray discs are totally equal to DVD discs. But blue rays can store up to 25–50 GB data, and also dual layer blue rays have double data storage as above. Blue rays are commonly used to store high definition (HD) videos because of its high storage capacity. Blue ray disc outlined as third generation of compact disc technology. This is also use optical technology to store data. [7]

Storage capability of optical storage device are categorized bellow.

Flash Memory devices

Flash memory is a non-volatile memory that use for data store and transfer data between computer and other digital device. Flash memory specially have ability to be electrically programed as well as erased. Flash memory commonly use in USB drives, digital cameras, mp3 players, and solid-state drives as well.

Flash memory made by the technology of EEPROM. It means electrically erasable programmable read only memory. But USB drive is standalone from that. Flash memory uses gateway transistor technology to store data. There are above some examples to flash memory.

USB Flash Memory

USB flash memory well known as USB drive. It is a plug and play storage device that can easily move here and there. A bootable USB can launch an OS or can run diagnostic for troubleshooting computer doubts. USB drives can be divided according to the amount of data it can store. Such as 2GB, 4GB, 8GB, 16GB etc. commonly using USB drives made by several components and the USB plug as interface for the host device. And a crystal oscillator to control output data of device. USB drives uses a NAND flash memory chip to data storing.

Memory cards

Well, known as flash memory card. Memory cards can store verity of data. Such as images, videos, pdfs, documents etc. memory cards mostly used in digital devices as data store on it. Digital cameras, mobile phones, mp3 players are examples.

Cloud Storage Devices

Cloud storage devices are some model of co computer data storage that stores digital data in logical pools. That is named cloud storage. Cloud storage allows user to save their files, documents in a privet network. The cloud provider hosts, security, to user and maintains the sever and ensures you have accessed the data server you need it. Cloud storage can be used as an alternative to the amount of space and space required for hard storage devices.

Computer hardware can only store a limited amount of data and will have to be moved to other devices once they run out of space. But not so far cloud storage. Cloud storages do not cost a lot of space and can be bought for a small fee. The following are some examples of cloud storage devices.

Google Drive

Google is an online cloud storage that is developed by google company. Google drive allows users to store their data and information on google servers across their devices. Google drive confine google sheets, google spread sheets, google docs, and google slides.

Google drive allows users to store up to 15GB capability of storage completely free of charge. Users of google drive can change privacy setting for their individual files and folders and, they can share those with other drive users making public content.

Dropbox

Dropbox is also a file hosting service that is owned by Dropbox, inc company. It gives cloud storage for personal cloud and file storage. That is also a software that can store users’ data and information without spending any hard space. Dropbox was found in 2007 by Drew Houstan and Arash Ferdowsi. This is same as google drive and uses same methods for data storing from users. Basically, a user can store his data up to 2GB in free of charge on Dropbox. And Dropbox offers paid planes starting from 2TB or more capability of storage.

Most used storage devices

Memory devices are used to store data from the computer from the user. Those devices can hold and store data permanently and temporarily. Secondary memory devices can hold data and information permanently as well as primary memory devices can hold data and information temporarily. Hard drive is a example for secondary memory and RAM is a example for primary memory.

Some storage devices are mostly used, and some are not often used. Bellow is a list of the most commonly used memory devices.

Hard Disk Drive.

Hard disk drive is a storage device that is mainly use as a storage device. That is located on CPU of the computer permanently. Hard disk drive is mainly use as main storage device on the computer. That is store some very important things such as operating system, software, and other important applications. That is why the hard disk drive is mostly used storage device.

The other mostly used storage devices can be lined up like below.

· Flash memory devices

· Punch cards

· DVD

· CD

· SSD

· Cloud storage

Characteristics of Computer Storage Devices

Storage technologies of all storage device can be differentiated by on the behavior. Those characteristics are categorized by volatility, mutability, accessibility, and addressability. [8]

a) Volatility

Can be divided as two main parts.

Non-volatile Memory

Non-volatiles can retain stored data and information when it not connected to power. It’s ideal method for storing information for a long time. Mostly secondary storage devices use this technology.

Volatile Memory

Requires power connection to store data. When user unplug the power connection stored data will be destroying. Volatile memory is the fastest technology to store data nowadays. Primary storage devices use this technology to store and retrieve data from user.

b) Differentiation

Have two different parts.

Dynamic Random-Access Memory

A part of volatile memory. Stored data should be re-read or rewrite from time to time and should be refresh it. Otherwise, data will be loss from memory.

Static Random-Access Memory

This also a form of volatile memory. Different than DRAM. It is not wanted to refresh frequently. But it loss the data when unplugged from power.

c) Accessibility

Random Access

Can be accessed to any location at any moment at same time. Suitable for primary and secondary storage.

Sequential access

Accessing of part of information will be in a serial order. On after one order. Therefore, access time to an information depends on what information was last accessed.

d) Mutability

Read/write storage or mutable storage

This allows user input information and data to be overwritten any time. A computer that is without amount of tread write storage of primary memory unless for many tasks.

Read only storage

Writes data on storage once after manufacture and read from storage many times. This action calls immutable. Immutable memories use for tertiary storages and offline storages.

Slow write, fast read storage

Read and write storage that can overwrite information in many times. But the write operation is slower than read operation. CD-RW, Flash memory are examples.