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Monday, 7 October 2013

Swap partition and Swap file addition

ØCreating 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


Ø 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


Ø To add a swap file:


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.

1.      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


2.      Setup the swap file with the command:
mkswap        /swapfile


3.      To enable the swap file immediately but not automatically at boot time:
swapon        /swapfile


4.      To enable it at boot time, edit /etc/fstab to include the following entry:
/swapfile          swap            swap    defaults        0 0

5.      The next time the system boots, it enables the new swap file.


6.      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.

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