Difference between revisions of "Swap"

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(Created page with "== Swap == Swap usage can lead to performance degradation of your server. So we highly recommend to disable swap space and increase the memory. How to disable swap space: ...")
 
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Swap usage can lead to performance degradation of your server. So we highly recommend to disable swap space and increase the memory.
 
Swap usage can lead to performance degradation of your server. So we highly recommend to disable swap space and increase the memory.
  
How to disable swap space:
+
===How to disable===
  
 
  root@vmsniff:~# swapoff -a
 
  root@vmsniff:~# swapoff -a
Line 16: Line 16:
 
  # swap was on /dev/sdb2 during installation
 
  # swap was on /dev/sdb2 during installation
 
  #UUID=4cf42564-4339-42ed-b7ec-29644a3085f1 none            swap    sw              0      0
 
  #UUID=4cf42564-4339-42ed-b7ec-29644a3085f1 none            swap    sw              0      0
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 +
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===How to configure===
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Most distributions have set by default to use swap when Ram usage exceeds 40%
 +
check your swappiness values with
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cat /pro/sys/vm/swappiness
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 +
You can change it in a run-time (after restart default swap settings will beback) , effect is instant
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echo '0' > /pro/sys/vm/swappiness
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 +
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You can set the value permanent adding line at end of /etc/sysctl.conf
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vm.swappiness=0
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 +
(The settings means to use swap only when there is no Ram free for latest kernels)
 +
 +
===Make swap empty===
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swapoff -a
 +
swapon -a

Revision as of 10:20, 7 May 2020

Swap

Swap usage can lead to performance degradation of your server. So we highly recommend to disable swap space and increase the memory.

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


How to configure

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

cat /pro/sys/vm/swappiness

You can change it in a run-time (after restart default swap settings will beback) , effect is instant

echo '0' > /pro/sys/vm/swappiness


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

vm.swappiness=0

(The settings means to use swap only when there is no Ram free for latest kernels)

Make swap empty

swapoff -a
swapon -a