Difference between revisions of "Swap"
| Line 25: | Line 25: | ||
(the value 60 here means to use the swap only when there is less then 60% of free RAM) | (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 | + | You can change it in a run-time,effect is instant after disable/enable the swap(but not persists restart of a server) |
| − | echo ' | + | echo '5' > /pro/sys/vm/swappiness |
You can set the value permanent by adding the line at end of /etc/sysctl.conf | You can set the value permanent by adding the line at end of /etc/sysctl.conf | ||
| − | vm.swappiness= | + | vm.swappiness=5 |
(0 value means to use swap only when there is no Ram free) | (0 value means to use swap only when there is no Ram free) | ||
Revision as of 18:46, 21 July 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
Note: use dmesg (or dmeg -T) command to ensure there is no service crashing because of no ram free.
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
(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' > /pro/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