Swap: Difference between revisions

Line 1:

Swap memory is a file-system based temporary storage for memory to allow a system to shuffle between different tasks that would otherwise consume all available physical memory (RAM). Cloud providers like [[AWS]]<ref>https://serverfault.com/questions/218750/why-dont-ec2-ubuntu-images-have-swap</ref> and [[Digital Ocean]]<ref>https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04</ref> do not setup swap on their default images. So, it's up to you to enable swap. RedHat provides ~~an overview of swap at~~ https://www.redhat.com/en/blog/do-we-really-need-swap-modern-systems

Swap memory is a file-system based temporary storage for memory to allow a system to shuffle between different tasks that would otherwise consume all available physical memory (RAM). Cloud providers like [[AWS]]<ref>https://serverfault.com/questions/218750/why-dont-ec2-ubuntu-images-have-swap</ref> and [[Digital Ocean]]<ref>https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04</ref> do not setup swap on their default images. So, it's up to you to enable swap. RedHat provides [https://www.redhat.com/en/blog/do-we-really-need-swap-modern-systems an overview of swap] where you can learn the basics of Virtual Memory Management, paging, swapping, and thrashing.

== Procedure ==

Here's a procedure that you can run as root, or an administrative user with sudo privileges.

# see if it's enabled?

Line 22:

Line 25:

swapon -s

# make it permanent in the file system

echo /swapfile none swap sw 0 0 | tee -a /etc/fstab

echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

# there are some other problems with a default Droplet

# swappiness is too high, and cache pressure is too high

cat << HERE >> /etc/sysctl.conf

cat << HERE | sudo tee -a /etc/sysctl.d/10-swap.conf

# swappiness for a VM should be closer to zero

# 60 might be good for a desktop

Line 38:

Line 41:

HERE

</syntaxhighlight>

== Feature ==

This is the subject of a feature request https://github.com/freephile/meza/issues/176

[[Category:System Administration]]

[[Category:Cloud]]

@@ Line 1: / Line 1: @@
-Swap memory is a file-system based temporary storage for memory to allow a system to shuffle between different tasks that would otherwise consume all available physical memory (RAM).  Cloud providers like [[AWS]]<ref>https://serverfault.com/questions/218750/why-dont-ec2-ubuntu-images-have-swap</ref> and [[Digital Ocean]]<ref>https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04</ref> do not setup swap on their default images.  So, it's up to you to enable swap.  RedHat provides an overview of swap at https://www.redhat.com/en/blog/do-we-really-need-swap-modern-systems
+Swap memory is a file-system based temporary storage for memory to allow a system to shuffle between different tasks that would otherwise consume all available physical memory (RAM).  Cloud providers like [[AWS]]<ref>https://serverfault.com/questions/218750/why-dont-ec2-ubuntu-images-have-swap</ref> and [[Digital Ocean]]<ref>https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04</ref> do not setup swap on their default images.  So, it's up to you to enable swap.  RedHat provides [https://www.redhat.com/en/blog/do-we-really-need-swap-modern-systems an overview of swap] where you can learn the basics of Virtual Memory Management, paging, swapping, and thrashing.
+== Procedure ==
+Here's a procedure that you can run as root, or an administrative user with sudo privileges.
 <syntaxhighlight lang="bash">
 # see if it's enabled?
@@ Line 22: / Line 25: @@
 swapon -s
 # make it permanent in the file system
-echo /swapfile   none    swap    sw    0   0 | tee -a /etc/fstab
+echo '/swapfile   none    swap    sw    0   0' | sudo tee -a /etc/fstab
 # there are some other problems with a default Droplet
 # swappiness is too high, and cache pressure is too high
-cat << HERE >> /etc/sysctl.conf
+cat << HERE | sudo tee -a /etc/sysctl.d/10-swap.conf
 # swappiness for a VM should be closer to zero
 # 60 might be good for a desktop
@@ Line 38: / Line 41: @@
 HERE
 </syntaxhighlight>
+== Feature ==
+This is the subject of a feature request https://github.com/freephile/meza/issues/176
 [[Category:System Administration]]
 [[Category:Cloud]]