Partition

 Partition

Partitioning is a means to divide a single hard drive into many logical drives. A partition is contiguous set of blocks on a drive that are treated as an independent disk.

Purpose of partition

Ease of use - Make it easier to recover a corrupted file system or operating system installation.

Performance - Smaller file systems are more efficient. You can tune file system as per application such as log or cache files. Dedicated swap partition can also improve the performance (this may not be true with latest Linux kernel 2.6).

Security - Separation of the operating system files from user files may result into a better and secure system. Restrict the growth of certain file systems is possible using various techniques.

Backup and Recovery - Easier backup and recovery.

Stability and efficiency - You can increase disk space efficiency by formatting disk with various block sizes. It depends upon usage. For example, if the data is lots of small files, it is better to use small block size.

Testing - Boot multiple operating systems such as Linux, Windows and FreeBSD from a single hard disk.

Types of partition

There are three types of partions are there .they are

Primary

A primary partition may contain an operating system along with any number of data files (for example, program files, user files, and so forth). Before an OS is installed, the primary partition must be logically formatted with a file system compatible to the OS. If you have multiple primary partitions on your hard disk, only one primary partition may be visible and active at a time. The active partition is the partition from which an OS is booted at computer startup. Primary partitions other than the active partition are hidden, preventing their data from being accessed. Thus, the data in a primary partition can be accessed (for all practical purposes) only by the OS installed on that partition.
If you plan to install more than one operating system on your hard disk, you probably need to create multiple primary partitions; most operating systems can be booted only from a primary partition.

Extended

An extended partition does not directly hold data. You must create logical partitions within the extended partition in order to store data. Once created, logical partitions must be logically formatted, but each can use a different file system.

Logical Partition

Logical partitions is partition that are created inside the extended partition

Partition Creation

 fdisk command is used to create a partition

d:deleate a partition

n:add a new partition

p:print partition table

q:quit without saving changes

w:write table to disk and exit

t:to select the type of partition

partprobe command is used to update the partition table

mkfs.<filesystem name>:used to format filesystem

mount <partition> <directory name> to mount the directory
 umount <directory name> to unmount the directory

Note: we have to use /etc/fstab to mount partition permanently

Example:

[root@raju]#vi /etc/fstab

/dev/sda4   /raju  ext4     defaults  0 0

[root@raju]#fdisk /dev/sda

command(mfor help):n

First cylinder (36495-38913, default 36495):

Using default value 36495

Last cylinder, +cylinders or +size{K,M,G} (36495-38913, default 38913): +100M

Command (m for help): w  [root@raju]#partx -a   /dev/sda

[root@raju]#mkfs.ext4 /dev/sda5

[root@raju]#mkdir /raju

[root@raju]#vi /etc/fstab

/dev/sda4   /raju  ext4     defaults  0 0