how to increase swap space in linux

8/12/2019 How to Increase Swap Space in Linux

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Question:I would like to add more swap space to my Linux system. Can you explain

with clear examples on how to increase the swap space?

Answer:You can either use a dedicated hard drive partition to add new swap space,

or create a swap file on an existing filesystem and use it as swap space.

How much swap space is currently used by the system?

Free command displays the swap space. free k shows the output in !".

# free -k

total used free shared buffers

cached

Mem: 3082356 2043700 1038656 0 50976

1646268

-/ buffers/cache: 346456 2735900

!"a: 4192956 0 4192956

#wapon command with option s, displays the current swap space in !".

# s"ao$ -s

%&le$ame '(e !&)e *sed

+r&or&t(

/de,/sda2 art&t&o$ 4192956 0 -1

#wapon s, is same as the following.

# cat /roc/s"as


+r&or&t(

/de,/sda2 art&t&o$ 4192956 0 -1

Method 1: Use a Hard Drive Partition for Additional wap pace

If you have an additional hard disk, $or space availa%le in an existing disk&, create a

partition using fdisk command. Let us assume that this partition is called 'dev'sdc(

)ow setup this newly created partition as swap area using the mkswap command as

shown %elow.

# mks"a /de,/sdc1

*na%le the swap partition for usage using swapon command as shown %elow.

# s"ao$ /de,/sdc1

+o make this swap space partition availa%le even after the re%oot, add the following

line to the 'etc'fsta% file.

# cat /etc/fstab

/de,/sdc1 s"a s"a defaults0 0


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erify whether the newly created swap area is availa%le for your use.

# s"ao$ -s


+r&or&t(

/de,/sda2 art&t&o$ 4192956 0 -1

/de,/sdc1 art&t&o$ 1048568 0 -2

# free -k


cached

Mem: 3082356 3022364 59992 0 52056

2646472

-/ buffers/cache: 323836 2758520

!"a: 5241524 0 5241524

!ote:In the output of swapon s command, the +ype column will say -partition if

the swap space is created from a disk partition.

Method ": Use a #ile for Additional wap pace

If you don/t have any additional disks, you can create a file somewhere on your

filesystem, and use that file for swap space.

+he following dd command example creates a swap file with the name -myswapfile

under 'root directory with a si0e of (1234" $(5"&.

# dd &f/de,/)ero of/root/m(s"af&le bs1M cou$t1024

10240 records &$

10240 records out

# ls -l /root/m(s"af&le

-r"-r--r-- 1 root root 1073741824 .u 14 23:47

/root/m(s"af&le

Change the permission of the swap file so that only root can access it.

# chmod 600 /root/m(s"af&le

4ake this file as a swap file using mkswap command.

# mks"a /root/m(s"af&le!ett&$ u s"asace ,ers&o$ 1 s&)e 1073737 k

*na%le the newly created swapfile.

# s"ao$ /root/m(s"af&le

+o make this swap file availa%le as a swap area even after the re%oot, add the

following line to the 'etc'fsta% file.

# cat /etc/fstab

/root/m(s"af&le s"a s"adefaults 0 0


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erify whether the newly created swap area is availa%le for your use.

# s"ao$ -s


+r&or&t(

/de,/sda2 art&t&o$ 4192956 0 -1

/root/m(s"af&le f&le 1048568 0 -2

# free -k


cached

Mem: 3082356 3022364 59992 0 52056

2646472

-/ buffers/cache: 323836 2758520

!"a: 5241524 0 5241524

!ote:In the output of swapon s command, the +ype column will say -file if the

swap space is created from a swap file.

If you don/t want to re%oot to verify whether the system takes all the swap space

mentioned in the 'etc'fsta%, you can do the following, which will disa%le and ena%le

all the swap partition mentioned in the 'etc'fsta%

# s"aoff -a

# s"ao$ -a

how to increase swap space in linux

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