- Sometimes you need to install multiple OS on single machine. For example, you want to install Windows as well as Linux on single machine, or you need to install multiple versions of windows on PC. this concept is called dual booting. Dual booting or multiple booting system allows you to have primary OS and an alternate OS which you use less frequently.
- The mechanism of dividing a single hardisk into multiple usable block so that it looks like there are multiple hardisk present. Example: windows file explorer showing drives such as C,D,E in single hardisk when it is divided.
Windows cant cope with multiple primary partition, means only one partition is visible and others are hidden
Out of 4 partition one is known as extended partition. Extended partition can be further divided into many logical partition.
In linux minimum 2 partitions need to be created
- Root partition: minimum size of root partition is 2GB to 8GB.
- Swap partition: the recomended size of partition is twice the size of RAM or 1GB.
The partition that OS is running from, referenced as root partition.
It is the top of the directory tree, and contains Linux and everything that you install with Linux and roughly equivalent to your “C:” drive under DOS or Windows.
Most OS supports virtual memory concept, where system hardisk functions as an extenstion to RAM, it is called Swap space.
When OS runs out of physical memory it move in or swap out the contents which are currently not needed form RAM to Swap partition to make room for new program that needs memory.
When OS need anything from Swapped memory it has to find something else to swap out and then it swaps in the required data from disk.
Boot loader helps to boot OS installed on system.
Linux OS lets you to select two boot loader, GRUB and LILO.
The first process that takes place after you turm on your computer is booting.
Process of booting takes place through boot sequence that consists of a set of instruction to start computer.