Swap

Some useful links to explain the concepts of Swap

Concepts

• https://www.linux.com/news/all-about-linux-swap-space

• http://www.linux-tutorial.info/modules.php?name=MContent&pageid=311

• http://aarvik.dk/what-is-swap-memory-and-how-to-use-it/

• http://blog.scoutapp.com/articles/2015/04/10/understanding-page-faults-and-memory-swap-in-outs-when-should-you-worry

Commands

• Check total swap space used & sort it descending

for file in /proc/*/status ; do awk '/VmSwap|Name/{printf $2 " " $3}END{ print ""}' $file; done | sort -k 2 -nr | head -10
for file in /proc/*/status ; do awk '/VmSwap|Name/{printf $2 " " $3}END{ print ""}' $file; done | awk  '{print $1 " " $2/1024 " MB" }'|sort -k 2 -n -r | head -10

• Alternatively - run below command

sudo nice top (Press Shift+o → p (To sort processes by swap usage)

Configuration

• http://www.cyberciti.biz/faq/linux-add-a-swap-file-howto/

• http://bencane.com/2016/05/18/creating-a-swap-file-for-tiny-cloud-servers/

• https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-centos-7

Troubleshooting & Log Parsing

• http://northernmost.org/blog/find-out-what-is-using-your-swap/

• http://www.digitalinternals.com/unix/linux-swap-usage-per-process/379/

• http://www.cyberciti.biz/faq/linux-which-process-is-using-swap/

• https://unix.stackexchange.com/questions/294600/i-cant-enable-swap-space-on-centos-7