What Is the Purpose of the Master Boot Record MBR on a Hard Drive?
- The Master Partition Table is one of two items in the Master Boot Record. It contains information about the hard drive's partitions. Partitions are the sections of a hard drive. One major purpose of partitions is to reduce cluster sizes. The cluster size is the smallest amount of space a file system allocates to store a file. If a file is smaller than this allotment, the remaining space is unused. Partitions allow for smaller file systems, smaller cluster sizes and less wasted space. The Master Partition Table contains information on the number and type of partitions and tells the computer which partition should be used to boot up.
- The Master Boot Code is the second item stored on Master Boot Record. It is the first program your computer runs each time it starts up. It is an initial boot program that the BIOS carries out in order to start up the computer. The BIOS (Basic Input/Output System) is a piece of software that creates an interface between the hardware and the operating system every time you turn on your computer.
- Hard drives store their information on magnetized disks called "platters." The platters are divided into concentric circles called "tracks" which in turn are split up into "sectors." This gives the drive a way of efficiently organizing and quickly retrieving data. The Master Boot Record is always located on the first sector of the first track.
- You turn your computer on, and the initial current runs to the CPU to clear out left-over data in its internal memory. The CPU then activates the BIOS. The BIOS checks the first sector of the hard drive's first track after performing a series of hardware tests. There it finds the Master Boot Record and runs the Master Boot Code. This consults the Master Partition Table, which tells the computer which partition to use to boot the system.
- Viruses known as "Boot Sector Infectors" target the Master Boot Record. This is because it contains code that is guaranteed to run every single time the computer turns on and before anything else happens on the computer, giving the virus a chance to spread as often as possible.
