Red Hat ADDING SWAP SPACE

7.2. ADDING SWAP SPACE

Sometimes it is necessary to add more swap space after installation. For example, you may upgrade the amount of RAM in your system from 128 MB to 256 MB, but there is only 256 MB of swap space. It might be advantageous to increase the amount of swap space to 512 MB if you perform memory-intense operations or run applications that require a large amount of memory.
You have three options: create a new swap partition, create a new swap file, or extend swap on an existing LVM2 logical volume. It is recommended that you extend an existing logical volume.

7.2.1. Extending Swap on an LVM2 Logical Volume

To extend an LVM2 swap logical volume (assuming /dev/VolGroup00/LogVol01 is the volume you want to extend):
  1. Disable swapping for the associated logical volume:
    swapoff -v /dev/VolGroup00/LogVol01
  2. Resize the LVM2 logical volume by 256 MB:
    lvm lvresize /dev/VolGroup00/LogVol01 -L +256M
  3. Format the new swap space:
    mkswap /dev/VolGroup00/LogVol01
  4. Enable the extended logical volume:
    swapon -va
  5. Test that the logical volume has been extended properly:
    cat /proc/swaps
    free

7.2.2. Creating an LVM2 Logical Volume for Swap

To add a swap volume group (assuming /dev/VolGroup00/LogVol02 is the swap volume you want to add):
  1. Create the LVM2 logical volume of size 256 MB:
    lvm lvcreate VolGroup00 -n LogVol02 -L 256M
  2. Format the new swap space:
    mkswap /dev/VolGroup00/LogVol02
  3. Add the following entry to the /etc/fstab file:
    /dev/VolGroup00/LogVol02   swap     swap    defaults     0 0
  4. Enable the extended logical volume:
    swapon -va
  5. Test that the logical volume has been extended properly:
    cat /proc/swaps
    free

7.2.3. Creating a Swap File

To add a swap file:
  1. Determine the size of the new swap file in megabytes and multiply by 1024 to determine the number of blocks. For example, the block size of a 64 MB swap file is 65536.
  2. At a shell prompt as root, type the following command with count being equal to the desired block size:
    dd if=/dev/zero of=/swapfile bs=1024 count=65536
  3. Change the persmissions of the newly created file:
    chmod 0600 /swapfile
  4. Setup the swap file with the command:
    mkswap /swapfile
  5. To enable the swap file immediately but not automatically at boot time:
    swapon /swapfile
  6. To enable it at boot time, edit /etc/fstab to include the following entry:
    /swapfile          swap            swap    defaults        0 0
    The next time the system boots, it enables the new swap file.
  7. After adding the new swap file and enabling it, verify it is enabled by viewing the output of the command cat /proc/swaps or free.
0 (0)
Article Rating (No Votes)
Rate this article
Attachments
There are no attachments for this article.
Comments
There are no comments for this article. Be the first to post a comment.
Full Name
Email Address
Security Code Security Code
Related Articles RSS Feed
Linux nslookup Command Examples for DNS Lookup
Viewed 512 times since Sat, Sep 29, 2018
3 Ways to Check Linux Kernel Version in Command Line
Viewed 666 times since Fri, Apr 19, 2019
Tcpdump Examples Linux
Viewed 2894 times since Fri, Nov 16, 2018
LVM basic
Viewed 737 times since Sat, Jun 2, 2018
linux unix aix banner /etc/issue
Viewed 510 times since Fri, Aug 3, 2018
logrotate Understanding logrotate utility
Viewed 256 times since Sun, Jan 12, 2020
Linux / UNIX: DNS Lookup Command
Viewed 433 times since Sun, Sep 30, 2018
Tilix: Advanced Tiling Terminal Emulator for Power Users
Viewed 1248 times since Thu, Apr 18, 2019
HowTo: Find Out Hard Disk Specs / Details on Linux
Viewed 549 times since Mon, Jan 28, 2019
Linux / UNIX: Run Command a Number of Times In a Row
Viewed 646 times since Tue, Aug 6, 2019