{"id":75,"date":"2021-09-15T14:17:00","date_gmt":"2021-09-15T14:17:00","guid":{"rendered":"https:\/\/bestdedicatedhosting.in\/blog\/?p=75"},"modified":"2021-11-02T13:12:20","modified_gmt":"2021-11-02T13:12:20","slug":"how-to-create-a-linux-swap-file","status":"publish","type":"post","link":"https:\/\/bestdedicatedhosting.in\/blog\/how-to-create-a-linux-swap-file\/","title":{"rendered":"How To Create a Linux Swap File"},"content":{"rendered":"\n
\n\n\n\n

Description <\/strong><\/p>\n\n\n\n

We will explain swap space, and learn how to create swap space using a swap file in Linux: this is important in case we don\u2019t have a swap partition created on the hard disk. <\/p>\n\n\n\n

Swap space\/partition is space on a disk created for use by the operating system when memory has been fully utilized. <\/p>\n\n\n\n

It can be used as virtual memory for the system; it can either be a partition or a file on a disk.<\/p>\n\n\n\n

When the kernel runs out of memory, it can move idle\/inactive processes into swap creating room for active processes in the working memory. <\/p>\n\n\n\n

This is memory management that involves swapping sections of memory to and from virtual memory.<\/p>\n\n\n\n

Below are the steps we can follow to create a swap space using a file.<\/p>\n\n\n\n

How to Create and Enable Swap in Linux <\/strong><\/p>\n\n\n\n

1.<\/strong> In this example, we will create a swap file of size 2GB<\/strong> using the dd command as follows. <\/p>\n\n\n\n

Note that bs=1024<\/strong> means read and write up to 1024<\/strong> bytes at a time and count = (1024 x 2048)MB<\/strong> size of the file. <\/p>\n\n\n\n

dd if=\/dev\/zero of=\/mnt\/swapfile bs=1024 count=2097152<\/em><\/strong><\/pre>\n\n\n\n
Alternatively, use the fallocate command<\/strong> as follows.
<\/p>\n\n\n\n
fallocate --length 2GiB \/mnt\/swapfile<\/em><\/strong>
<\/pre>\n\n\n\n
And then set the appropriate permissions on the file; make it readable only by root user as follows.
<\/p>\n\n\n\n
chmod 600 \/mnt\/swapfile<\/em><\/strong>
<\/pre>\n\n\n\n
2.<\/strong> Now setup the file for swap space with the mkwap command<\/strong>. <\/p>\n\n\n\n
mkswap \/mnt\/swapfile<\/em><\/strong><\/pre>\n\n\n\n
3.<\/strong> Next, enable the swap file and add it to the system as a swap file. <\/p>\n\n\n\n
swapon \/mnt\/swapfile<\/em><\/strong>
<\/pre>\n\n\n\n
4.<\/strong> Afterwards, enable the swap file to be mounted at boot time. Edit the \/etc\/fstab<\/strong> file and add the following line in it. <\/p>\n\n\n\n
\/mnt\/swapfile swap swap defaults 0 0<\/em><\/strong>
<\/pre>\n\n\n\n
In the line above, each field means: <\/p>\n\n\n\n
  •  \/mnt\/swapfile<\/strong> \u2013 device\/file name <\/li>
  •  swap<\/strong> \u2013 defines device mount point <\/li>
  •  swap<\/strong> \u2013 specifies the file-system type <\/li>
  •  defaults<\/strong> \u2013 describes the mount options <\/li>
  •  0<\/strong> \u2013 specifies the option to be used by the dump program <\/li>
  •  0<\/strong> \u2013 specifies the fsck command option <\/li><\/ul>\n\n\n\n
    5.<\/strong> To set how often the swap file can be used by the kernel, open the \/etc\/sysctl.conf<\/strong> file and add the line below. <\/p>\n\n\n\n
    Note that the default value of how frequent swap space can be used is 60<\/strong> (maximum value is 100<\/strong>).<\/p>\n\n\n\n
     The higher the number, the more frequent swap space utilization by the kernel. When the value is set to 0<\/strong>, the swap file will only be used if the operating system has fully utilized memory.<\/p>\n\n\n\n
    vm.swappiness=10<\/em><\/strong>
    <\/pre>\n\n\n\n
    6.<\/strong> Now verify the swap file was created using the swapon command<\/strong>.<\/p>\n\n\n\n
    swapon  -s 

    OR
    free 

    OR 
    cat  \/proc\/swaps <\/pre>\n\n\n\n
    We can optionally reboot the system to effect the above changes using the following command.<\/p>\n\n\n\n
    reboot<\/em><\/strong><\/pre>\n\n\n\n
    We hope you\u2019ve found this useful!  <\/p>\n","protected":false},"excerpt":{"rendered":"
    Description We will explain swap space, and learn how to create swap space using a swap file in Linux: this is important in case we don\u2019t have a swap partition created on the hard disk. Swap space\/partition is space on a disk created for use by the operating system when memory has been fully utilized. […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_eb_attr":"","footnotes":""},"categories":[4],"tags":[],"class_list":["post-75","post","type-post","status-publish","format-standard","hentry","category-linux"],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/posts\/75","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/comments?post=75"}],"version-history":[{"count":1,"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/posts\/75\/revisions"}],"predecessor-version":[{"id":76,"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/posts\/75\/revisions\/76"}],"wp:attachment":[{"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/media?parent=75"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/categories?post=75"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bestdedicatedhosting.in\/blog\/wp-json\/wp\/v2\/tags?post=75"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}