COMPUTER STORAGE DEVICES
Storage devices play a vital role in the computer system by storing data, porting different data, and enabling the user to extract data files conveniently. These devices can store information or data both permanently and temporarily. All storage devices store data in the binary format in 0 or 1, Storage devices can be divided based on many features. One of the features that is necessary to check is the storage capacity, it is the amount of data a specific storage device can hold. Most commonly used storage devices at present include the Hard disk, Optical disks and USB flash drives all of which will be further discussed in this article.
WHY DO WE NEED STORAGE DEVICES?
Storage devices are a core component of any computer. The main purpose or usage of a storage device is storing data, applications, and other firmware virtually on a computer. The type of storage media to use will depend on what kind of data and size of data that is stored and mainly according to the device on which the storage media is used.
Primary storage devices which are known as the “Main Memory”, is used to store data and application data temporarily while the computer is turned on (Volatile). Primary storage devices are used to processing data needed for the computer to perform tasks. For example, RAM which is a volatile memory used to store data needed for functioning of the computer applications and software faster than secondary storage devices like hardware. Secondary storage devices which are known as “Auxiliary Memory”, will store data for a long time even after turning off power (Non-Volatile). Can store personal user data, applications, and other data for longer periods of time.
In simple terms we can use storage devices to store, to extract and to transport data from one source to another.
As mentioned earlier storage devices can be divided into many categories based off their distinct features. One such method includes division of storage devices as primary, secondary tertiary and offline storage devices.
CLASSIFICATION: 1
Primary storage devices
When we consider about primary storage devices these are small in size and mostly composed of the computer’s internal memory. These devices are constructed with integrates circuits and semi-conductor components. This type is also referred to as the main memory because it helps the computer to do basic tasks.
It accesses data from the central processing unit of the computer sing different memory buses. Memory buses are the components which connects the central processing unit with the storage area of the chip. Few examples for primary storage include RAM, ROM and cache.
RAM
Random Access Memory or RAM is used to store data temporarily and it stores data that is being used quickly, meaning the data goes away when you switch off the computer. However, it is very useful as it is faster than the other types of storage units such as hard disks. It allows the user to run applications faster and more efficiently. There are different types of RAMS, such as Static RAM, Dynamic RAM and Synchronous Dynamic RAM.
When we compare the two types of SRAM and DRAM, SRAM is more power consuming, expensive and it is faster than DRAM. It is not needed to refresh SRAM however DRAM must be refreshed thousand times per second.
ROM
When we consider the next type of primary storage ROM, it refers to Read Only Memory. In contrast to RAM, we won’t lose the data on switching off the computer. Every computer comes with a small amount of ROM containing boot firmware which tells the computer how to start up. This is done by a small code containing instructions. It contains permanent and semi-permanent type of stored data. Many ROM chips are located on the motherboard of the computer, and these are essential to boot up the computer and data input and output systems
CACHE
The next example is cache memory is a storage unit which is readily available that RAM and acts as a temporary storage compartment from which the CPU can get data efficiently. Its memory is also known as central processing unit. Generally, it has a size lower than the main memory. However, it is much faster than RAM.
Cache memory is also called as CPU memory due to the fact that it is located very close to the CPU to increase the efficiency. Cache memory is further categorized based on the closeness to the micro-processing unit. They are Level 1, which is smaller and fastest connected to the CPU, Level 2 or the secondary cache which could be located on the CPU or elsewhere. L2 is connected to the CPU by a different bus system, so that when the main system has traffic it doesn’t affect the overall system much. Level 3 helps the overall functioning of both L1 and L2, however it is much slower than them.
SECONDARY STORAGE
Unlike the primary storage, secondary storage cannot be directly accessed by the CPU. It can be either internally or externally connected and it gives the user to store data beyond primary storage. Secondary storage is a non-volatile type of storing meaning that it doesn’t go away when the computer power is switched off. These are much slower compared to primary storage devices. Earlier secondary storage devices were internal, however in the present there are many external storage units.
Few examples of storage devices include Hard disk, Magnetic storage devices, Optical storage devices and Flash memory.
HARD DISK
Computer functioning required operating systems which enables the user to use different software. To install this software the computer needs a hard drive. Hard drive provides the storage necessary for the operating system. It is the main storage unit which has a very large storing capacity. It can be within the computer attached to the motherboard. These consists of circular plates coated with a magnetic substance. When we apply a magnetic field iron particles on the magnetic disk can be polarized by magnetizing tiny spots on the rotating. When the circular disk starts spinning, a read / write arm moves it from right to left.
Tertiary storage
This involves a robotic mechanism that insert and remove data on to the storage devices, this is mostly used to massive amount of data which is not used frequently due to its slow nature. The main purpose of this type of storage is to give a large storing capacity at a low cost. Two examples for tertiary storage devices are magnetic disk and optical disk.
MAGNETIC DISKS
Magnetic disks are cheap and small. It contains a strip which is coated from magnetic substance which can be encoded. Hence it easily can be transported from one place to another. In other words, it is portable, but it requires an external tape drive to read it. Magnetic disks uses serial access to access into data which makes it slower. Serial access means it starts from the beginning until it finds the necessary piece of information, unlike hard disks which gives direct access. It can also store data up to terabytes which is quite advantageous.
OPTICAL DISKS
Optical storage involves any device that uses optical technology to store data, and which uses low power laser beams to store write and read data. Drives which can read and write information to these disks are known as magneto-optic. Few popular optical disks are blue ray disks, compact disks (CDs), digital versatile disks (DVD). Blue ray disks hold the most amount of data.
OFFLINE STORAGE
This type of storing requires the user to connect it to the computer every time they want to use it hence it’s not built into the computer as some previously mentioned methods of storing. It is portable and mostly used as a backup storage. Few examples for offline storage include floppy disk zip diskette, USB Flash drive, memory card.
Memory card
Memory cards is a storage device that stores different type of files ranging from media files to data files. It is classified to be permanent and a non-volatile form of storage meaning it will not erase its content after power is switched off. They are small and usually portable. It can be used by connecting it to the computer.it enables you to take information from one device to another and easily work on them. It is commonly referred as a flash card. Digital cameras, phones, printers usually use memory cards.
Floppy disk
It uses a magnetic storage medium, and it contains thin, soft magnetic strips on the disk, which is enclosed in a hard casing. To be able to write or read it requires a floppy disk drive. It can be used to transfer and store data as a backup. These are portable and have less storage capacity than hard drives which makes them fairly cheap. There are three main types of floppy disks 8 inch, 5^1/4, 3^1/4
Zip diskette
These are another form of storage that uses magnetic technologies. And this is similar to floppy disks but more advanced and the magnetic film applied on the disk is of high quality. Same as the floppy disk these are also used to store, transfer and back up data, only difference being that it can store more data than the floppy disks. It needs a special zip disk drive to read and write data. It is portable
USB Flash drive
This a very small, portable, and durable form of storage which uses flash memory and universal serial bus interface. In this type of storage usually higher the storage it is faster. It is also known as solid state storage. It is supported by all operating systems, and it contains several components. USB plug is the portal which connects the flash drive to the computer, USB mass storage controller which contains a little amount of RAM and ROM. NAND flash memory chip which stores all the data and a crystal oscillator which output the data to the user.
Memory card Floppy disk Zip diskette USB
CLASSIFICATION 2:
Magnetic storage devices
Magnetic storage is a type of storing which utilizes magnetism. As mentioned earlier digital data are stores in 1’s or 0’s, and magnetic fields have two poles to represent those two values. Magnetic storage involves non-volatile storage which means it doesn’t erase the data once the power is switched off. The technology behind this is read or write heads move closer to the disk, and as they move, they can detect any change in the magnetism from one region to another and records it in 1’s and 0’s. As it uses the read or write technology it is reusable, meaning that we can delete the previous information and write it again. And the ability to store large amount of data is seen as an advantage among this type of storing, however it is slow in nature which is perceived as a disadvantage.
Few examples of this type include floppy disk, magnetic tape, hard drive.
Optical storage
Optical storage involves any storage type that uses laser beams to read and write data. Due to its durability and portability, it was expected that it’ll replace hard disk at one time. However, the low growth in optical storage limited it to a type of storage that can be used as a backup storage. Few examples of this type include CD’s, DVDs, and Blue-Ray disks. These blue ray disks are perceived to be superior to CDs and DVDs since CD’s and DVD’s use red wavelength and blue ray disks as the name suggests uses blue wavelength which enables it to have a bigger capacity. The science behind this technology is that it encodes digital data in the form of pits on to these disks with the help of laser beams.
Flash memory
Flash memory is a type of storage used in computers and other electronic devices which can store data even with less power and due to its ability to erase all data at once it got the name “flash”. This is a solid-state storage. It has an electronically erasable programable and read only form of memory.
The technology in this type of storage includes two types of transistors the control gate and the floating gate. They are both separated by a small oxide layer. When both gates are connected both cells read a value 1. To covert, it to 0, a voltage is passed via control gate to the floating gate which makes the electrons move into the floating gate enabling it to store data with no power.
Online cloud storage.
Cloud storage is a popular method of storage at present which enables most businesses and other users to store large amount of data and access it whenever and wherever with the permission. This method is currently so popular due to the reason that it also enables to work collaboratively on different projects. It enables the user to store and retrieve data easily given that there’s an internet connection. Google drive and drop box are few examples of cloud storage at present. In simple terms clod storing stores data in several servers in different locations and it uses a logical memory system. There are different services provided by cloud service providers such as
1. Software as a service (SaaS)
2. Platform as a service (PaaS)
3. Infrastructure as a service (IaaS)
Cloud storage can be further divided into,
Public cloud
Private cloud
Community cloud
Hybrid cloud
CHARACTERISTICS OF STORAGE DEVICES
There are many characters related with storage devices which contribute to their function. And it is important to have an idea about it so we can choose the best storage device for or expected function.
When considering about different characteristics, one of the major features includes its capacity. In simple terms it is how much data it can hold. It also refers to the disk space it has. The capacity can be measured in bits or bytes. An example for a storage device with less space is floppy disk whereas an example for a device with large volume of space is hard disk.
Another distinct feature is its speed. In this digitalized world speed is common to both humans and electronic devices. Here the speed refers to how fast a computer can read and write data from the given storage device. It is measured in bytes per second.
Another distinct feature is portability. It is the ability to take the device from one place to another easily, which enables the user to carry out different tasks not limited to a specific place. Small size and light weight contribute to portability. Portable storage devices are usually powered directly through the USB port.
Another very important characteristic of storage devices is their durability, here in addition to withstanding physical movements, this specifically refers to for how long the device can hold the data on it with no bit rot or data loss. Some storage devices are used to store large amounts of financial data and archived data in business use. Hence to store those type of data we must ensure that our device is durable to make sure it doesn’t cause redundancy of data.
Another feature, the reliability refers to will the storage device function as expected at the required time. It is also how well we can rely on the device to save data properly and let the user access it when they need to.
No matter how good the storage device it must give value for its cost. Cost may refer to cost per MB or the cost of the whole device. Even if we obtain a device with a higher cost per MB if we do not use the entire space, it is a waste of money. Hence it is important to pay attention to the cost of the storage device. (characteristics-of-storage-types)
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