How do you add swap to an EC2 instance?

amazon-web-services amazon-ec2 out-of-memory
ajtrichards picture ajtrichards · Jun 18, 2013 · Viewed 139.7k times · Source

I'm currently running an ec2 micro instance and i've been finding that the instance occasionally runs out of memory.

Other than using a larger instance size, what else can be done?

Answer

ajtrichards picture ajtrichards · Jun 18, 2013

A fix for this problem is to add swap (i.e. paging) space to the instance.

Paging works by creating an area on your hard drive and using it for extra memory, this memory is much slower than normal memory however much more of it is available.

To add this extra space to your instance you type:

sudo /bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024
sudo /sbin/mkswap /var/swap.1
sudo chmod 600 /var/swap.1
sudo /sbin/swapon /var/swap.1

If you need more than 1024 then change that to something higher.

To enable it by default after reboot, add this line to /etc/fstab:

/var/swap.1   swap    swap    defaults        0   0

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