Difference between revisions of "Swap"

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== Swap ==  
 
== Swap ==  
  
Swap usage can lead to performance degradation of your server. So we highly recommend to disable swap space and increase the memory.
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Swap usage leads to performance degradation of your server. So we highly recommend to configure swap space properly or disable it entirely
 
 
===How to disable===
 
 
 
root@vmsniff:~# swapoff -a
 
 
 
Then edit the /etc/fstab file and comment out the swap lines. E.g.
 
 
 
proc            /proc          proc    defaults        0      0
 
# / was on /dev/md0 during installation
 
UUID=17e56a9a-0f42-44ca-90e8-570315708def /              xfs    relatime        0      1
 
# swap was on /dev/sda2 during installation
 
#UUID=0a403f5e-0505-4055-a219-70217b6b74d1 none            swap    sw              0      0
 
# swap was on /dev/sdb2 during installation
 
#UUID=4cf42564-4339-42ed-b7ec-29644a3085f1 none            swap    sw              0      0
 
 
 
Note: use dmesg (or dmeg -T) command to ensure there is no service crashing because of no ram free.
 
  
 
===How to configure===
 
===How to configure===
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  swapoff -a
 
  swapoff -a
 
  swapon -a
 
  swapon -a
 +
 +
===How to disable===
 +
 +
root@vmsniff:~# swapoff -a
 +
 +
Then edit the /etc/fstab file and comment out the swap lines. E.g.
 +
 +
proc            /proc          proc    defaults        0      0
 +
# / was on /dev/md0 during installation
 +
UUID=17e56a9a-0f42-44ca-90e8-570315708def /              xfs    relatime        0      1
 +
# swap was on /dev/sda2 during installation
 +
#UUID=0a403f5e-0505-4055-a219-70217b6b74d1 none            swap    sw              0      0
 +
# swap was on /dev/sdb2 during installation
 +
#UUID=4cf42564-4339-42ed-b7ec-29644a3085f1 none            swap    sw              0      0
 +
 +
Note: use dmesg (or dmeg -T) command to ensure there is no service crashing because of no ram free.

Revision as of 13:37, 20 October 2021

Swap

Swap usage leads to performance degradation of your server. So we highly recommend to configure swap space properly or disable it entirely

How to configure

Most distributions have set by default to use swap when Ram usage exceeds 40% check your swappiness values with

cat /proc/sys/vm/swappiness

(the value 60 here means to use the swap only when there is less then 60% of free RAM)

You can change it in a run-time,effect is instant after disable/enable the swap(but not persists restart of a server)

echo '5' > /proc/sys/vm/swappiness


You can set the value permanent by adding the line at end of /etc/sysctl.conf

vm.swappiness=5

(0 value means to use swap only when there is no Ram free)

Make swap empty

swapoff -a
swapon -a

How to disable

root@vmsniff:~# swapoff -a

Then edit the /etc/fstab file and comment out the swap lines. E.g.

proc            /proc           proc    defaults        0       0
# / was on /dev/md0 during installation
UUID=17e56a9a-0f42-44ca-90e8-570315708def /               xfs     relatime        0       1
# swap was on /dev/sda2 during installation
#UUID=0a403f5e-0505-4055-a219-70217b6b74d1 none            swap    sw              0       0
# swap was on /dev/sdb2 during installation
#UUID=4cf42564-4339-42ed-b7ec-29644a3085f1 none            swap    sw              0       0

Note: use dmesg (or dmeg -T) command to ensure there is no service crashing because of no ram free.