Add Swap Memory on Debian 10
Checking no active swap with free -h and swapon --show command
#/usr/sbin/swapon --show
#free -h
total used free shared buffers cached
Mem: 492M 451M 41M 17M 125M 204M
-/+ buffers/cache: 120M 371M
Swap: 0B 0B 0B
No swap space active, then checking available space on the hdd
#df -h Filesystem Size Used Avail Use% Mounted on /dev/xvda2 20G 1.8G 17G 10% / udev 10M 0 10M 0% /dev tmpfs 99M 13M 87M 13% /run tmpfs 247M 0 247M 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 247M 0 247M 0% /sys/fs/cgroup
Plenty of space available on the disk with /. ,Generally, an amount equal to or double the amount of RAM on your system is a good starting point.
CREATING SWAP FILE
Since the server as 512MB of RAM, we will create a 512MB file in this guide. Type the following command to create 512MB swap file (1024 * 512MB = 524288 block size):
#dd if=/dev/zero of=/swapfile bs=1024 count=524288
Sample outputs:
524288+0 records in 524288+0 records out 536870912 bytes (537 MB) copied, 3.23347 s, 166 MB/s
Where,
if=/dev/zero : Read from /dev/zero file. /dev/zero is a special file in that provides as many null characters to build storage file called /swapfile1. of=/swapfile1 : Read from /dev/zero write storage file to /swapfile1. bs=1024 : Read and write 1024 BYTES bytes at a time. count=524288 : Copy only 523288 BLOCKS input blocks.
We can verify that the correct amount of space was reserved by typing:
#ls -lh /swapfile -rw-r--r-- 1 root root 489M Nov 3 06:56 /swapfile
Enabling the file as swap and swap space
#chmod 600 /swapfile
#/usr/sbin/mkswap /swapfile Setting up swapspace version 1, size = 499996 KiB no label, UUID=a81f762c-ef8a-40b5-a845-52aed148aeea
#/usr/sbin/swapon /swapfile
Verify that the swap is available by typing:
#/usr/sbin/swapon --show NAME TYPE SIZE USED PRIO /swapfile file 488.3M 0B -1 #free -h total used free shared buffers cached Mem: 492M 456M 35M 17M 125M 205M -/+ buffers/cache: 125M 367M Swap: 488M 0B 488M
Our swap has been set up successfully
Making the Swap File Permanent, by adding the swap file to our /etc/fstab
#cp /etc/fstab /etc/fstab.bak #echo '/swapfile none swap sw 0 0' | tee -a /etc/fstab
Tuning Swap by Adjusting the Swappiness and Cache Pressure Setting
Set vm.swappiness and vm.vfs_cache_pressure value automatically by add the line to bottom of /etc/sysctl.conf
#vim /etc/sysctl.conf vm.swappiness = 10 vm.vfs_cache_pressure = 50
Check the current swappiness value by typing:
cat /proc/sys/vm/swappiness 60
For a Desktop, a swappiness setting of 60 is not a bad value. For a server, you might want to move it closer to 0. Set the swappiness to a different value by using the sysctl.For instance set the swappiness to 10
#sysctl vm.swappiness=10 vm.swappiness = 10
Set value automatically by adding the line to bottom of /etc/sysctl.conf
#vim /etc/sysctl.conf vm.swappiness=10
Save and close the file when you are finished.
Check the current Cache Pressure Setting
Configures how much the system will choose to cache inode and dentry information over other data.
#cat /proc/sys/vm/vfs_cache_pressure 100
Set this to a more conservative setting like 50 by typing:
#sysctl vm.vfs_cache_pressure=50 vm.vfs_cache_pressure = 50
Set value automatically by adding the line to bottom of /etc/sysctl.conf
#vim /etc/sysctl.conf vm.vfs_cache_pressure=50
Save and close the file when you are finished.
Source : From https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-debian-10