My Ubuntu server not using available swap, even if OOM. What to do?

Posted on January 24, 2014

I recently added 1 GB of swap to my Ubuntu server to prevent MySQL crashes on RAM overloading. I followed this tutorial: https://www.digitalocean.com/community/articles/how-to-configure-virtual-memory-swap-file-on-a-vps.

I use htop to monitor resources. When I use loadimpact to test my server it crashes when no more RAM is available, but not a single byte of swap is used…

I got the current setting now:

swapon -s

Filename Type Size Used Priority /var/swap.img file 1023996 0 100

free

               total       used       free     shared    buffers     cached

[…] Swap: 999 0 999

/etc/fstab contains: LABEL=DOROOT / ext4 errors=remount-ro 0 1 /var/swap.img none swap defaults,pri=100 0 0

Last note: when I used the tutorial I get the following msg executing “swapon -p 100 /var/swap.img” : swapon: /var/swap.img: swapon failed: Device or resource busy

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