Storage Devices
Definition of Computer Storage Devices
Storage devices are used to store data and information. One of the most important function of the modern computer. Any computer hardware that is used for storing, transferring, or extracting data files and objects is referred to as this. Information can be held and stored in storage devices both temporarily and permanently. They can be both external and internal to a computer.[1]
Depending on whether it is considered discrete in nature, a storage device may also be referred to as a storage medium or storage media.[1] There are so many types of devices that we can use for relevant specific task. Each of them with its benefits and drawbacks.
Why we use storage devices?
Storage devices are used to store data and information digitally. If we don’t have those devices, we must have to keep our data and information manually as the past. But this way has so many drawbacks. Because this can be harm to our data. Not safe and data can be destroyed by any effect. And we need much space to keep them. Then the usage of storage devices is they can minimize those difficulties. Computer can store data and information in a digital format. Then there are so many benefits use storage devices rather than manual form.
At the present all are worked with computers. So, we must have to keep our data and information in a computer. A computer without a storage device is considered a dumb terminal because it cannot save or recall any settings or information.
Here, we have so many benefits as, don’t need much space to store data, can secure from proper security method, and if the data lost suddenly, we can keep backups as well. Although a computer can operate without a storage device, it can only read data unless it is connected to another computer with storage capabilities. Even simple tasks like browsing the Internet necessitate the storage of data on your computer.
Storage is required not only for the storage of files, but also for the execution of tasks and applications. Any file you create or save on your computer is saved to the storage device on your computer. This storage device also store your computer’s operating system and any application
As computers improve, so do the technologies used to store data, necessitating more storage capacity. People are requiring more and more space, and they want it faster, cheaper, and portable. This necessitates the development of new technologies. When new storage devices are designed, and users upgrade to them, the older devices become obsolete and are no longer used. As an example, in a first generation we used punch card as a storage device but gradually we came to second generation and we replaced to floppy disk.
Types of Storage
There is a traditional division guided by cost per bit. According to that there are main four types of storage. They are,
1. Primary Storage
2. Secondary Storage
3. Tertiary Storage
4. Off-line Storage
Primary Storage
The primary store, often known as memory, is the only one that can directly access to the CPU. The CPU read the instructions stored on there on a continuously and executes them as needed. Any data that is being actively worked on is also stored there in a consistent manner..[2]
There are three types of primary memory
1. RAM
2. ROM
3. Cache Memory
RAM (Random Access Memory)
RAM temporarily stores data. The data stored in RAM will be deleted when the computer is switched off. Therefore, this is also called volatile memory. Data coming from input devices as well as data sent to output devices are held in RAM. When comparing to ROM, which is discussed after this, RAM has both read-write facility. This memory called as Random Access Memory, because data of this can access fast than all the other data.
There are two types of RAM.
- SRAM (Static Random Access Memory)
SRAM consist of flip-flop which is consist of 6 transistors to keep a bit. This used primary for cache and registers. Each cell will maintain its data as long as it has electricity power. SRAM can operate extremely quickly. Static RAM is used to create the speed-sensitive cache.
2. DRAM (Dynamic Random Access Memory)
DRAM is the most common type of memory use today as main memory. Each memory cell is made up of two parts: a transistor and a capacitor. The capacitor holds the bit of information. The transistor provides electricity to change the status of the capacity. The problem with the capacitor’s bucket is that it has a leak. Therefore, need to refresh the capacitor thousands of times per second.
ROM (Read Only Memory)
The data in Read Only Memory is not erased when the computer is switched off. The information is permanently stored in the memory during the manufacture. Therefore, it is a Non-volatile Memory. The commands required for booting up a computer are stored in ROM. ROM stored instructions that are required to start the computer. These commands are called BIOS (Basic Input Output System). Computer Manufacturing companies store these commands in a ROM with a smaller capacity and is connected to the mother board. ROM memory cannot be easily or quickly overwritten or modified.
There are various types of ROMs. Such as,
· MROM
· PROM
· EPROM
· EEPROM
Cache Memory
The Central Processing Unit checks cache memory first to see whether the required data is available for processing. However, if the required data is not available then the data is fetched to cache memory from RAM for processing. There are some levels of cache differentiate by speed of access and size. The fastest cache closer to the CPU register.
Secondary Storage
Secondary storage, sometimes known as external memory or auxiliary storage, is not directly accessible by the CPU, unlike primary storage. The computer’s input/output channels are typically used to access secondary storage and move data to primary storage. secondary storage is non-volatile memory (retaining data when its power is shut off). [2] In modern computer hard disk usually used as secondary storage.
Hard Disk
A hard disk drive (HDD) is a non-volatile data storage device . It is commonly mounted inside in a computer, directly connected to the motherboard’s disk controller. It consists of one or more platters enclosed in an airtight case. When a magnetic head moves quickly over the platters as they spin, data written to them.
The hard drive is the main, and usually largest data storage device in a computer. It has a storage capacity ranging from 160 GB to 2TB.
The maximum capacity will increase with technology development. Hard disk speed is the speed at which content can be read and written on a hard disk. A hard disk unit comes with a set rotation speed varying from 4500 to 7200 rpm. Disk access time is measured in milliseconds.
A typical HDD architecture includes a spindle that carries flat circular disks known as platters that hold the recorded data. Non-magnetic materials, such as aluminum alloy, glass, or ceramic, are used to make the platters. They are coated with a thin layer of magnetic material, typically 10–20 nm thick, and a protective layer of carbon.[3]Information is written to and read from a platter as it rotates past device called read and write heads the are positioned to operate very close to magnetic surface, with their flying height often in the range of 10s of nanometers. [3]
During formatting, the drive creates circular tracks around the disk’s surface, then divides each track into sectors. The OS organizes sectors into groups, called clusters, then tracks each file’s location according to the clusters it occupies.
Tertiary Storage
Tertiary storage, often known as tertiary memory, is the next level of storage after secondary storage. It usually entails a robotic mechanism that mounts (inserts) and dismounts removable mass storage media into a storage device in accordance with the system’s requirements; such data is frequently duplicated to secondary storage before usage. Because it is substantially slower than secondary storage, it is mostly used for preserving seldom accessed information. This is most effective for really huge data repositories that can’t be accessed by humans.[2] It is a comprehensive computer storage system that is usually very slow, so it is usually used to archive data that is not accessed frequently.
Magnetic tapes and optical disk can take under the tertiary storages.
Magnetic Tapes
A magnetically coated strip of plastic on which data can be encoded. Tapes for computers are similar to tapes used to store audio. Tape is much less expensive than other storage mediums but commonly a much slower solution that is commonly used for backup. Used mostly in sever computers for back up due to its larger storage capacity. But tape is not used in day today life as it is slow in reading and writing.[4]
Optical Disc
Optical storage is term for storage of data on a optically readable medium. Data is recorded by marking marks on a disc that can be read back with the aid od light. A common modern technique used by computers involves a tiny beam of laser light precisely focused on a spinning disc. The most common types of optical media are
– Blu-ray Disc (BD)
– Compact Disc (CD)
– Digital Versatile Disc (DVD)
Offline Storage
Offline storages are devices are devices that store computer data but these are not controlled by the processing unit. The medium is recorded and then physically removed or unplugged, usually in a secondary or tertiary storage device. This must operate by a human before accessing the computer. It cannot be retrieved without human intervention, unlike tertiary storage. There are some devices can take under the offline storage. They are,
· Floppy Disc
A soft magnetic disk. Floppy disks are portable. Floppy disks are slower to access than hard disks and have less storage capacity, but they are much less expensive. Can store data up to 1.44MB. Two common sizes: 5 ¼” and 3 ½”.
· Zip Diskette
Hardware data storage device developed by Iomega that functions like a Standard 1.44" floppy drive. Capable to hold up to 100 MB of data or 250 MB of data on new drives.
· USB Flash Drive
A small, portable flash memory card that plugs into a computer’s USB port and functions as a portable hard drive. Flash drives are available in sizes such as 2GB, 4GB, and up to 256GB and are an easy way to transfer and store information.
· Memory Cards
An electronic flash memory storage disk commonly used in consumer electronic devices. Memory cards are usually read by connecting the device containing the card to your computer, or by using a USB card reader.
Types of Computer Storage Devices
Magnetic Storage Devices
Data must be stored in digital format in computer systems. Magnetic data storage is one of the most extensively utilized methods of digital data storage. Any method of data storage that uses a magnetic media is referred to as this. Binary data, which is data in the form of zeros and ones, makes up digital data. Magnetic polarities are divided into two categories, each of which represents either zero or one.
Magnetic storages are non-volatile. The data is not erased when the computer is power off. Magnetic storage is frequently utilized because, in compared to other storage technologies, it is comparatively inexpensive. Magnetic storage is read-write, allowing you to reuse the store space by removing older data. It also has a big storage capacity, making it ideal for storing enormous amounts of data. The main disadvantage of magnetic storage is the slowness with which data may be accessed.
There are different types of magnetic storages. Some are,
· Floppy Disk
· Hard Drive
· Magnetic Tapes
Floppy Disk
IBM introduced the floppy disk in 1969. The “Floppy Diskette” is another name for a floppy disk. It is a data storage medium used in personal computers that is made of hardware. A floppy disk is a plastic cartridge with a protective shell that is 3.5 inches square and is about 2 millimeters thick. Internally, iron oxide was utilized to coat the floppy disk in order to store data in magnetic form, just like a hard drive. However, floppy disks are now utterly outdated.
Hard Drive
A hard drive (HDD) is a physical storage area where all of your data (files and folders) is kept in magnetic form. It has a storage capacity of more than 200 GB. All data is kept on the hard drive, which is made up of a stack of disks that are mounted internally with strong encasement. These disks spin at a much faster rate (5500 to 7500 RPM), allowing data to be recovered quickly from any location on the hard drive. After the power supply is turned off, all data on the hard drive is not lost.
Magnetic Tapes
In 1928, Fritz Pfleumer invented magnetic tape, with the primary goal of using it being to record voice. It is an older technology that has been supplanted by CDs and DVDs. Used mostly in sever computers for back up due to its larger storage capacity. But tape is not used in day today life as it is slow in reading and writing.[5]
Optical Storage Devices
Optical storage is term for storage of data on a optically readable medium. Data is recorded by marking marks on a disc that can be read back with the aid of light. A common modern technique used by computers involves a tiny beam of laser light precisely focused on a spinning disc.
A motor rotates the disc. A laser beam is hit onto the surface of the disk. The light is scattered by the pits and reflected by the lands/bumps. A light sensitive diode picks up the reflected laser light and convert into digital data, these two variations encode the binary 0’s and 1’s. CD, DVD, Blu-ray Disc can take under this.
CD
CD-ROM stands for “Compact Disc Read Only Memory,” and it is a device that belongs to the “Random Access” category. These discs can store about 700 MB of digital data. These data can’t be thrown away due to a blunder.
DVD
The term “DVD-ROM” stands for “Digital Versatile Disc — Read Only Memory,” and it is a type of device that belongs to the “Random Access” category. DVD-ROM discs can hold up to 4.7 GB of data, while the storage capacity of a Dual Layer DVD device is double that. These discs are used to store high-definition video.
Blu-ray Disc
DVDs have completely overtaken Blue Ray discs since these discs can carry data up to 25–50 GB and double layer Blue Ray discs can store double data. Blue Ray CDs are used to store HD (High Definition) videos because of its large storage capacity.[6]
Flash Memory Devices
Dr. Fujio Masuoka first created flash memory in 1980. Because a piece of code, such as programming, may be written and erased electrically, flash memory is also known as EEPROM (electronically erasable programmable read only memory).
Computers and electronic devices such as USB flash drives, MP3 players, digital cameras, and solid-state drives require flash memory to store data. Because all data is saved in the memory when the power is turned off, flash memory is non-volatile.
Flash Memory can divide into four types based on user requirements. They are,
1. Traditional Flash Storage
2. Server Flash Storage
3. The all flash Array
4. Hybrid Array
Flash memory can divide into two types based on the technology. They are,
1. NOR Flash Memory
All programs and instructions are saved in NOR flash memory, and these programs are run using NOR flash without accessing any copied data into Main Memory. Although NOR flash memory has a faster reading speed than NAND flash memory, it has a slower write and erase performance. It has a good cost-effectiveness in the 1–4 MB capacity range.
2. NAND Flash Memory
NAND memory is the greatest solution for accessing many other types of block devices, such as hard disks. If you require more data storage capacity, NAND flash memory is an excellent choice. It provides higher tech density and expands capacity at a low cost. It can perform faster erases, consecutive writes, and sequential reads.
There are various devices under the flash devices.
USB Flash Drive
This has become a very popular flash memory device due to its easy portability and the ability to read and write data fast. This is also known as pen drive, USB thumb drive.
Memory Cards
This has the same function of USB flash drive. However, the method of connecting to the computer is different and it is smaller in physical size. This is used in digital cameras, mobile phones and computer gaming devices.
SSD
SSD stand for Solid State Drive. This is a type of non-volatile memory that can store and access many sorts of data. It has no moving parts, resulting in faster access times, quieter operation, greater dependability, and lower power usage.[8]
Online Cloud Storage Devices
Cloud storage, while not technically a device, is the newest and most adaptable sort of computer storage. Cloud storage means “the storage of data online in the cloud” wherein a data is stored in and accessible from multiple distributed and connected resources that comprise a cloud. Here servers situated in data centers all over the world, rather than a single location or thing. You’re saving a document on these servers when you save it to the cloud. Because cloud storage stores everything online, it saves space by not using any of your computer’s secondary storage.
Cloud storage can provide the benefits of greater accessibility and reliability; rapid development; strong protection of data backup, archival and disaster recovery purposes. The storage capacity of cloud storage is far more than that of USB flash drives and other physical storage options. This way, you won’t have to go through each device to find the right file.
External hard drives and solid-state drives (HDDs and SSDs) were formerly popular because of their portability, but they, too, fall short when compared to cloud storage. There aren’t many external hard drives that are small enough to fit in your pocket. They are still physical devices, despite being smaller and lighter than a computer’s internal storage drive. The cloud, on the other hand, may accompany you everywhere you go without taking up physical space or exposing you to the physical risks of an external drive.
External storage devices have also become popular as a speedy way to transfer files, but they’re only helpful if each actual device can be accessed. As many firms increasingly function remotely. You’re unlikely to send a USB drive to a colleague in another country to transfer a large file. Cloud storage acts as a link between distant workers, allowing them to collaborate easily from afar.
Examples: -
· Google drive
· iCloud
· SkyDrive
· Dropbox
Most Used Storage Devices
There are so many storages devices under different types. They are mentioned in above. But all those devices are do not use recently. Some are out of the use like magnetic tapes are do not use much. But there are some storage devices mostly used. At the present some devices are that we can see everywhere and every time. Those storage devices we can take as most used storage devices. They are,
· External Hard drive
· USB drive
· Memory card
· CD and DVD
External Hard Drive
External hard drive is not placed on a computer, it is a portable storage device. This is connected to the computer though USB or FireWire connection. When you take an external hard drive out of the hard drive casing, you’ll notice that the internal hard drive has the same internal structure as the computer’s hard disk. External hard drives are commonly used to back up computers or serve as a network drive since they have large storage capabilities.
USB drive
USB flash drives are used for supplemental storage, backup, data transfer between computers, and product distribution. They can also be used to boot the computer and hold an operating system. USB drives with ever-increasing storage capacities have effectively rendered writable CDs and DVDs useless.
CD and DVD
Since data stored digitally on a disk is read and written by laser beam, it is called optical media. Optical media is commonly used to carry data and information and there are several types. CD and DVDs are also under the optical media devices.
Memory Card
A memory card, sometimes known as a memory cartridge, is an electronic data storage device that uses flash memory to store digital data. These are commonly used in portable electronic devices like digital cameras, mobile phones, and allow adding memory to such devices without compromising ergonomy because the card is usually contained within the device rather than protruding like USB flash drives.
Characteristics of computer storage devices
Once we understand the many types of storage devices, we must also understand the various features of storage types in order to determine the most appropriate storage. Because we expect the capacity to access our data in a variety of ways, a variety of storage solutions had to be developed.
Certain key characteristics can be used to differentiate storage devices at all levels of the storage hierarchy. Capacity, portability, speed, durability, reliable, cost are the four core features.
References
[1] “What is a Storage Device? — Definition from Techopedia.” https://www.techopedia.com/definition/1119/storage-device (accessed Oct. 11, 2021).
[2] “Computer data storage — Wikipedia.” https://en.wikipedia.org/wiki/Computer_data_storage (accessed Oct. 11, 2021).
[3] “Hard disk drive — Wikipedia.” https://en.wikipedia.org/wiki/Hard_disk_drive (accessed Oct. 12, 2021).
[4] “Magnetic tape — Wikipedia.” https://en.wikipedia.org/wiki/Magnetic_tape (accessed Oct. 13, 2021).
[5] “Magnetic Storage Devices: Examples, Types, Advantages, Disadvantages.” https://digitalthinkerhelp.com/what-is-magnetic-storage-definition-devices-examples-and-types/ (accessed Oct. 14, 2021).
[6] “Optical Storage Devices: Examples, Types, Advantages, Disadvantages.” https://digitalthinkerhelp.com/what-is-optical-storage-types-devices-examples-advantages-disadvantages/ (accessed Oct. 14, 2021).
[7] “Optical disc — Wikipedia.” https://en.wikipedia.org/wiki/Optical_disc (accessed Oct. 14, 2021).
[8] “Flash Memory: Definition, Types, Examples, Devices, Advantage, Disadvantage.” https://digitalthinkerhelp.com/flash-memory-definition-types-examples-devices-advantage-disadvantage/ (accessed Oct. 14, 2021).
[9] “Characteristics of Storage Types | TeachAllAboutIT.” https://teachallaboutit.school/characteristics-of-storage-types/ (accessed Oct. 16, 2021).