Swap Management - II

Advanced Swap management

Actually its advantageous if we create swap partition separately if the server is not having any raw space left what we can do ? At any cost we have to increase the swap to improve the system productivity 

To come out of this situation there is one solution provided by Linux e.i we can create a swap file with in all ready existing and using partition if that partition is having sufficient free space

Step1:Switch off all the swap before any swap management

#swapoff -a

Step2:Determine what is the swap size we required(here i am taking 128MB) and execut the following command with count equal to 131072 (because 131072 is equal to 128M)

#dd if=/dev/zero of=/swapfile bs=1024 count=131072

Step3:Now set this swap file in order to use this file as swap

#mkswap /swapfile

Step4:Edit the /etc/fstab file to specify the swap file for perminient swap space

#vi /etc/fstab

/swapfile    swap    defaults    0 0

:wq

Step5:Update the kernel about the mount table changes

#mount -a

Step6:After managing the swap on the swap

#swapon -a

Step6:Check weather the swap space is updated or not by using following commands

#free -m   

#swapon -s 

#cat /proc/swaps

 

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Removing swap:

Step1:Before doing any thing with swap first we have to switch of the swap

#swapoff -v /swapfile

Step2:Remove/comment the entry of swap from /etc/fstab file

#vi /etc/fstab

then save and exit

Step3:update the kernel about mount table changes

#mount -a

Step4:Remove the swapfile permanently 

#rm /swapfile

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Swap management

Swap management - I

Step1:First check what is the swap space the system is having and utilization of swap size

#free -m   

#swapon -s 

-s for st

#cat /proc/swaps

this will give output of swap statistics in Megabytes(m), if we want the output in Kilobytes then free -k

Step2:Before starting the Swap management we have to take precautions such as switch off all the swap and no user should be logged in  

#swapoff -a

Step3:Check in the system if there is any raw space in the system

#fdisk -l

Step4:If the system is having free space then create a partition which support swap(partition type 82) with required amount of free space

#fdisk /dev/hda

p                #press p to print the partition table

n                #press n for creating new partition

256M          #specify the amount of swap required

t                 #press t to change the partition type to 82 (because partition type 82 is well supported for swap)

8                 #enter the partition no on which u want to create swap(here i am creating on /dev/hda8 partition)

82               #specifying the partition type

p                 #press p to print the partition table and to just conform the /dev/hda8 partition type

w                #press w for writing the changes to partition table (if suppose if u have any problem or trouble just                                           press q to quit from fdisk utility without any problem)

Step5:update the partition table changes to kernel so that there is no need to restart the system/server

#partprob

Step6:Permanently mounting the partition details,in order to do this one we have to update the /etc/fstab file

#vi /etc/fstab

/dev/hda8    swap    swap    defaults    0 0

enter the above entires in to fstab file,save it and exit from editing /etc/fstab file

:wq

Step7:formatting/creating swap signature on the newly created partition

#mkswap /dev/hda8

Note:stpe6 and step7 are interchangeable.

Step8:update the mount table to kernel

#mount -a

Step9:now on the swap so that it can be available for use.

#swapon -a

Step10:check weather the swap is updated or not

#free -m   

#swapon -s 

#cat /proc/swaps

---

Removing swap:

Step1:Before doing any thing with swap first we have to switch of the swap

#swapoff -a

Step2:Remove/comment the entry of swap from /etc/fstab file

#vi /etc/fstab

then save and exit

Step3:update the kernel about mount table changes

#mount -a

Step4:Remove the partition used by swap

#fdisk /dev/hda8

d                #press d to delete the partition

8                #specify the partition no to be deleted 

w                #press w to write the changes to partition table and quit the fdisk utility

Step5:update the partition table changes to kernel with out rebooting the system/server

#partprobe

Step6:now on the swap 

#swapon -a

Step7:now check weather swap is updated properly or not

#free -m   

#swapon -s 

#cat /proc/swaps

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