1606125255-week67.pptx for ICT Assignment
- 1. Introduction to ICT • Storage • Data access methods • Magnetic disk, hard disk, optical disc • Flash storage • Cloud storage • Disk partition
- 2. Storage • Storage is used to store data, information and programs permanently and is also known as secondary storage. • It is non-volatile as its contents remain safe if computer is turned off. • Storage is required for the following reasons – Main memory is a temporary memory. – The capacity of main memory is limited
- 3. Storage Device • A storage device is a hardware unit used to store and retrieve data to and from a storage medium.
- 4. Storage Device • Two important functions of a storage device are reading and writing. • Reading is the process of copying data and instructions from the storage medium to the storage device. • Writing is the process of copying data and instructions from the storage device to storage medium.
- 5. Storage Device • A storage device can be compared on the basis of following characteristics • Capacity: it is the maximum amount of data that can be stored. It is usually measured in gigabytes or terabytes. • Speed: speed is measured by access time and data transfer rate.
- 6. Storage Device • Access time is the time in which a device locates an item on a storage medium and is measured in milliseconds (ms). • Transfer rate is the speed with which data can be transferred to and from a device. It is measured in kilobytes/second (KBps), megabyte/second(MBps), gigabyte/second (GBps).
- 7. Basic units of data storage • Basic units of data storage are as follows – Bit: Computer works with binary digits. These digits are in the form of 0’s and 1’s. A binary digit is called bit. One bit takes one storage location in memory. It is the smallest unit for data storage. – Byte: A collection of eight bits is called byte. It is used to store single character. The capacity of the memory or the storage is expressed in terms of bytes.
- 8. Basic units of data storage • Kilobyte: A kilobyte consists of 1024 bytes. It is denoted by KB. • Megabyte: A megabyte consists of 1024 kilobytes. It is denoted by MB. • Gigabyte: A gigabyte consists of 1024 megabytes. It is denoted by GB. • Terabyte: A terabyte consists of 1024 gigabytes. It is denoted by TB
- 9. Difference between memory and storage
- 10. Data Access Methods • Different methods of accessing data from secondary storage devices are – Random access method – Sequential access method
- 11. Data Access Methods • Random access method – Random access means that data can be retrieved directly from any location on the storage medium in any order. – Random access devices move directly to a particular location on the medium when data located at that location is needed. – Almost all storage devices used with computers today are random access devices such as hard drives, CD/DVD drives and USB flash drives. – It is also known as direct access method.
- 12. Data Access Methods • Sequential access method – Sequential access means that data can be retrieved in the same order in which it is stored on the medium. – The data can not be accessed directly. – This method reads the data from the beginning and continues reading data until the required data is found. – This is a slow and time consuming method and is not commonly used.
- 13. Magnetic Disk • Magnetic disk use magnetic material to store data, instructions and information on disk surface. • The data on magnetic disks is stored in tracks and sectors. • Tracks form circles on the surface of a magnetic disk. • Each track is divided into sectors and each sector typically stores upto 512 bytes of data. • Hard disk is the most widely used magnetic disk.
- 14. Hard Disk • Hard disk is the primary storage device in a computer to store the programs and data permanently. • It is also known as hard disk drive (HDD) or hard drive (HD).
- 15. Hard Disk • A hard disk drive is a non-volatile data storage device. • It is usually installed internally in a computer, attached directly to the disk controller of the computer's motherboard. • It contains one or more platters, housed inside of an air-sealed casing. • Data is written to the platters using a magnetic head, which moves rapidly over them as they spin.
- 16. Hard Disk • Internal hard disks reside in a drive bay, connected to the motherboard using a SATA cable. • They are powered by a connection to the computer's PSU (power supply unit). • Examples of data stored on a computer's hard drive include the operating system, installed software, and the user's personal files.
- 17. Why does a computer need a hard drive? • A computer requires an operating system to allow users to interact with and use it. • The operating system interprets keyboard and mouse movements and allows for the use of software, like an Internet browser, word processor, and video games. • To install a computer operating system, a hard drive is required. • The hard drive provides the storage medium where the operating system is installed and stored.
- 18. Why does a computer need a hard drive? • A hard drive is also required for the installation of any programs or other files you want to keep on your computer. • When downloading files to your computer, they are permanently stored on your hard drive or another storage medium until they are moved or uninstalled.
- 19. Hard drives in modern computers • Modern computers often use an SSD (solid-state drive) as the primary storage device, instead of an HDD. • HDDs are slower than SSDs when reading and writing data, but offer greater storage capacity for the price. • Although an HDD may still be used as a computer's primary storage, it's common for it to be installed as a secondary disk drive. • For example, the primary SSD may contain the operating system and installed software, and a secondary HDD may be used to store documents, downloads, and audio or video files.
- 20. Hard drive components • A hard drive consists of the following components: the head actuator, read/write actuator arm, read/write head, spindle, and platter. • On the back of a hard drive is a circuit board called the disk controller or interface board. This circuit is what allows the hard drive to communicate with the computer.
- 21. Hard Drive: Storing Capacity • The hard drive is often capable of storing more data than any other drive, but its size can vary depending on the type of drive and its age. • Older hard drives had a storage size of several hundred MB (megabytes) to several GB (gigabytes). • Newer hard drives have a storage size of several hundred gigabytes to several TB (terabytes). • Each year, new and improved technology allows for increasing hard drive storage sizes.
- 22. External Hard Drives • Although most hard drives are internal, there are also stand-alone devices called external hard drives or portable hard drives that backup data on computers and expand the available space. • External drives are often stored in an enclosure that helps protect the drive and allows it to interface with the computer, usually over USB, eSATA, or FireWire. • External hard drives come in many shapes and sizes. • Some are large, about the size of a book, while others are about the size of a large smartphone.
- 23. Optical Disk • Optical disk is a form of removable storage. • Optical drives use a laser to read and write data on optical disk. • The most common types of optical media are Blu-ray, CDs, and DVDs. • Computers can read and write to CDs and DVDs using a CD writer or DVD writer drive, and a Blu-ray is read with a Blu-ray drive.
- 24. Optical Disk • A CD drive can only read CDs, a DVD drive can only read DVDs and CDs, and a Blu-ray drive can read CDs, DVDs, and Blu-ray discs. • CDs can store up to 700 megabytes (MB) of data, and DVDs can store up to 8.4 GB of data. • Blu-ray discs, which are the newest type of optical media, can store up to 50 GB of data.
- 25. Optical Disk • With the popularity of streaming content and downloading content from the Internet, the popularity of all optical media has greatly reduced. • Also, the reduced price of USB flash drives that store a lot more data have made optical media a less popular storage solution.
- 26. Flash Memory • Flash memory is a non volatile memory. • It does not need continuous power to retain the data and is more expensive than magnetic storage. • Data stored on flash memory storage can be erased and new data can be written. • Flash memory is widely used with cell phones, digital cameras, PDAs, solid-state drives and tablets.
- 27. Flash Memory: USB Flash Drive • USB flash drive is a flash memory storage device that is connected to a USB port in computer or mobile device. • It is very easy to use because it is light in weight and small in size. • It is commonly used to transfer documents, photos, music and videos from one computer to other. • It is available in different shapes, sizes and capacities. • It can store up to 256 GB of data or more.
- 28. Cloud Storage • Cloud storage is a service for the computer and mobile users to store their data online. • This service is provided and managed by cloud storage service provider in data centers that may consist of hundreds of servers to store data. • The data center can be located anywhere in the world, and users can also access their data from anywhere in the world using internet.
- 29. Cloud Storage • Some service providers, provides storage for specific media such as photos while other allows users to store any type of data and provide backup services. • Cloud storage also allow users to share data with other people. • Some important examples are DropBox, Apple iCloud, Google Drive and Microsoft OneDrive.
- 30. Cloud Storage • OneDrive: – It is a cloud storage service provided by Microsoft. – It can be used to store any type of data. – The files are stored by their type and can be searched easily. – This service can be accessed from computer and mobile devices. – One must signup for a Microsoft account to use One Drive. – It provides 15GB of free space for storing file and more space can be purchased if required.
- 31. Cloud Storage • DropBox: – It is a popular cloud storage service that is reliable and easy to use. – Users can store and access their files at any time using DropBox's website, desktop application or mobile application. – Any type of file can be stored and service automatically synchronizes the files across all devices. – It provides 2 GB free space on signup and user can also buy more space if required. – There is no limit on file size.
- 32. Cloud Storage • Google Drive: – It is a cloud storage service from Google. – Any user with a google account can access this service using Google drive website as well as desktop or mobile application. – It provides different services such as word processor, spreadsheet application and presentation builder. – It provides 15 GB of free space and maximum file size can be up to 10 GB.
- 33. Disk Partition • The process of partitioning a hard drive into separate logical areas is known as disk partitioning. • It is a disk management technique. • Physical capacity of a hard drive is divided into separate logical areas known as partitions. • Partitions work as independent hard drives and are also known as logical drives. • Each partition is labelled such as C Drive, D Drive, E Drive.
- 34. Disk Partition • Many new personal computers come with teo partitions, C drive is usually for operating system and D drive is used to store other applications and data. • Multiple partitions can be used to install two different operating systems on the same hard dtive such as windows and Linux.
- 35. Disk Partition • Storing data files on separate partition makes it easier to search them. • It also enables the users to back up all data files easily by backing up the entire partition containing data. • Formatting a partition must be done carefully as deleting a partition erases all data on that partition.
- 36. Disk Partition • Windows usually creates two basic types of partitions: primary partition and secondary partition.
- 37. Disk Partition • Primary Partition is a type of partition that can be uses as system partition. • It contains hardware specific files required to load windows. • A primary partition can be created to occupy the entire hard disk or a portion. • The primary partition should be formatted as a single logical drive only, it cannot be divided into multiple logical drives
- 38. Disk Partition • Extended Partition is a type of partition that can be divided into sub-partitions known as logical drives. • A hard disk can have only one extended partition. • Extended partition can be formatted to create drives. • Any number of drives can be created on an extended partition unlike primary partition and each of these drive can be designated by an alphabet.