Linux system add swap virtual memory and delete configuration method

　　

Brother even Linux training tutorial Linux system add swap virtual memory and delete configuration (www.lampbrother.net)

1.swap overview

swap partition, swap area, swap space can be simply described as: when the system's physical memory is not sufficient, it is necessary to release some of the space in physical memory for use by the currently running program. The freed space may come from programs that have not been manipulated for a long time, and the freed space is temporarily saved to swap space, waiting for those programs to run, then from swap . This way, the system is always swap interchange when there is insufficient physical memory. In fact, swap 's adjustment to linux server, especially web server performance is critical. By adjusting the swap , it is sometimes possible to bypass system performance bottlenecks and save system upgrade costs.

　　2. Create Swap

Because you forgot to create a swap partition when installing the Centos 6.0 operating system, an alarm occurs when you use Zabbix to monitor the server. Only then did you find that the swap partition was not created. So you need to create a swap partition that works as follows:

First, a user with ROOT access via SSH remote login or local terminal log in to the system, to create a swap partition

　　DD If=/dev/zero Of=/swap/swap bs=1024 count=1024000

　　If// input

　　of // output

　　Bs// block size

　　count// Total size

Create a Linux swap file

　　Mkswap/swap/swap

Activate /swap/swap swap file now

　　Swapon/swap/swap

See if it takes effect

　　[Email protected] ~]# free-m

　　Total used free shared buffers Cached

　　MEM:2007 140 1867 0 8 35

　　-/+ buffers/cache:96 1911

　　swap:972 0 972

As you can see from the output above, the swap partition has been successfully created.

Set to permanent effect

Although it is now in effect, wait until the next time the server restarts. The swap virtual disk will fail to be valid for permanent use, and you will need to add the following instruction set in the /etc/fstab file:

　　echo "/swap/swap swap swap defaults 0 0" >>/etc/fstab

So far, theswap partition has finished creating.

　　2. Delete a swap partition

Sometimes you may need to delete a swap partition, how do you delete the partition correctly ?

First stop the swap partition

　　Swapoff/swap/swap

Delete a swap partition file

　　Rm-rf/swap/swap

Delete "/etc/swap" specified file

This allows you to manually add and remove swap partitions.

Copy the code code as follows :

　　Sed-i "/' \/swa\/swap Swap swap defaults 0 0 '//"/etc/fstab

Linux system add swap virtual memory and delete configuration method