How to increase swap size in linux

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Swap is a type of filesystem and is a virtual memory. Whenever your RAM is full, your operating system will look for further memory in your swap space. For this reason, you reserve some part of the hard disk to create a swap partition.


Identifying Current Swap Space Usage:

root@vishal-desktop:/# cat /proc/swaps
Filename                                Type            Size    Used    Priority
/dev/sda7                               partition       1951740 4       -1

Alternatively, use the swapon command:

root@vishal-desktop:/# swapon -s
Filename                                Type            Size    Used    Priority
/dev/sda7                               partition       1951740 4       -1


Finally, the free command may also be used:

root@vishal-desktop:/# free
             total       used       free     shared    buffers     cached
Mem:        895112     721656     173456          0      36592     310156
-/+ buffers/cache:     374908     520204
Swap:      1952736          4    1952732



root@vishal-desktop:/# dd if=/dev/zero of=/swap bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 17.4283 s, 61.6 MB/s

Configure the file as swap:

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

root@vishal-desktop:/# chmod 600 /root/swap


root@vishal-desktop:/# mkswap /swap
Setting up swapspace version 1, size = 1048572 KiB


Enable the newly created swapfile :

root@vishal-desktop:/#  swapon /swap


# cat /etc/fstab
/swap  none  swap  sw  0 0


root@vishal-desktop:/#  swapon -s
Filename                                Type            Size    Used    Priority
/dev/sda7                               partition       1951740 142884  -1
/swap                                   file            1048572 0       -2

root@vishal-desktop:/#  free -k
                     total       used       free     shared    buffers     cached
Mem:        895112     828484      66628          0       2144     539552
-/+ buffers/cache:     286788     608324
Swap:      3000312     142876    2857436


root@vishal-desktop:/#  swapoff -a

root@vishal-desktop:/#  swapon -a



root@vishal-desktop:/# swapoff /newswap


Thanks,
Vishal Vyas