Section 1.1: Identifying the Principals of Personal Storage Devices and Backup Media
The storage devices allow you to store data on your PC (Personal Computer). The storage devices can be fixed or removable. Usually the hard disks are fixed devices and CDs (Compact Disks), DVDs (Digital Versatile Discs), and FDDs (Floppy Disk Drives) are removable storage devices. The details of different storage devices that can be used on a PC are as follows:
- Floppy Disk Drives: The FDDs are small and removable storage devices which were widely in use till 1987. They record data in a circular magnetic film, which is enclosed in a protective rectangular thin plastic shell. The first floppy disks that were widely used commercially were 5.25-inch disks that could store data up to 360 KB. Later high-density 3.5-inch floppy disks came into existence. They had hard shell cases for protection and could store up to 1.44 MB of data. Some 3.5-inch floppy disks utilized only one side of the internal magnetic mylar film for recording data and had the capacity of 744 KB. Some others were ultra-high-density disks that could store up to 2.88 MB of data.
- Optical Drives: The optical disks use laser instead of magnetic film to store data. The optical drives or writers allow users to create or burn their own CDs/DVDs. They appear, as shown in Figure 1. There are many different types of optical drives available these days, such as:
- CD-ROM drives: The CD ROMs are available as CD-R (Compact Disk -Recordable) or CD-RW (Compact Disk - ReWritable). A single CD can store up to 650 - 700 MB of data. The CD-R disks are read only drives and data once written cannot be erased from them. The CD-RW disks on the other hand are read write disks and allow data to be rewritten on them after erasing data from them.
- DVD-ROM drives: The DVD-ROMs use a slightly different technology and therefore can store up to 4 GB of data, which is about 6 times the size of a regular CD. DVDs look quite similar to CDs however, they are little thick as compared to CDs. The drives used to read/write DVDs can also read/write CDs. The DVD drives are also available as - DVD-R or DVD+R and DVD-RW or DVD+RW similar to CD drives.
- BLU-RAY drives: Blu-ray disks can store more information than a standard DVD disk using the same optical technology. They can hold from 50GB to 400 GB of data. These days they are more in use to record movie files than data files. They are available in two data formats, BD-R for recording PC data and PD-RW for rewritable media.
Section 1.1.1: Removable Storage
The removable storage mediums are usually used to take backups because they can be quickly ejected or taken out. This allows the backups to be stored at a different and safe location. Some of the removable storage devices are:
- Tape drives: This is a backup device that can be installed internally or externally in a PC. They use magnetic tape medium instead of disks for storing data. They can store much more data as compared to any other storage medium but are very slow. The most common use of tape drives is the archival storage.
- Solid state drives: This is a storage device that uses solid state memory to store data and is soon going to replace the traditional hard disk drive. The principle behind solid state drives is that there is no moving part in them. For example it does not have spinning platters and moving heads. The data stored is split into word length pieces and stored in memory. It is then accessed almost instantaneously using unique system-wide addresses. This behavior is in use in RAM for many years. Solid state disks use either NAND flash or SDRAM, which are non-volatile and volatile storage types respectively. The example of a solid state drives is a flash drive. It is not only used for computers but can also be used in digital cameras and MP3 players. The SD (Secured Digital) cards are a type of flash drive. The capacity of a standard SD card is 4 GB, SDHC (Secure Digital High Capacity) is 32 GB, and SDXC (Secure Digital Extended Capacity) is 2 TB. The SDHC and SDXC are the two standards of SD cards.
- External drives: The external hard drives are becoming common these days.
They are portable hard drives that store information on a hard drive that is not inside the computer. They usually connect to the computer through the USB port and a high-speed interface cable, which allows the external hard drive to communicate with the computer. External drives are very useful because they allow the user to back up or store important information such as sensitive documents, large music files, DVD images, movies, disk images, and even a backup of the contents of your main internal hard drive safely.