Swap Partition

Swap Partition

Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space.

While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory.

Swap space can be a dedicated swap partition (recommended), a swap file, or a combination of swap partitions and swap files.

The size of your swap should be equal to twice your computer's physical RAM for up to 2 GB of physical RAM. For physical RAM above 2 GB, the size of your swap should be equal

Some of useful commands in Swap creation

 mkswap:used to format the partition with swap file system

 swapon:to turnon the swap

swapoff:to turnoff the swap

Creation of swap partition

To accomplish this task you must be login form root account. So first login from root and verify your hard disk status with fdisk –l command ( This command will show that where your hard disk is mounted. You should use the mount point which show in the output of this command. For example if you see /dev/hda then you should use fdisk /dev/hda in next command. Or if you see /dev/sdb then you should use fdisk /dev/sdb in next command.

 [root@raju]#fdisk /dev/sda

command(mfor help):n

command(mfor help):e

First cylinder ("36495-38913", default 36495):

Using default value 36495

Last cylinder, +cylinders or +size{K,M,G} ("3649538913", default 38913): +500M

Command (m for help):t  Command (m for help): 82        #file type of swap space is 82 so change file type to 82 of this newly created partition  Command (m for help): w [root@raju]#Partx -a  /dev/sda [root@raju]#mkswap –f /dev/sda5 [root@raju]#swapon –a /dev/sda5 [root@raju]#swapon –s Mounting swap partition [root@raju~]#vi /etc/fstab /dev/sda4   swap swap defaults 0 0 [root@raju~]#mount –a

To remove the swap partition

Turnoff swap

[root@raju~]#swapoff /dev/sda5

Remove the entry from rc.local

Remove the partition from /etc/fstab

Reboot the system