How to add swap to and Amazon EC2 instance running Ubuntu 12.04 LTS?

Question

default Ubuntu 12.04 LTS doesn\'t create swap for some reason. Is there \"proper\" way to add it after install?

root@aux3:/root# df -h
Filesystem      Size  Used Avai         


        

Answer 1

Perhaps you're looking for this: http://inprvt.com/index.php/blogs/entry/how-to-add-swap-space-on-a-linux-based-ec2-server

See the second approach. You need to re-partition your ephemeral storage device. I'd put something along these lines to /etc/rc.local:

umount /dev/xvdb # in case it is already mounted
sfdisk /dev/xvdb << EOF
,1024,82
,
;
;
EOF
mkswap /dev/xvdb1 && swapon /dev/xvdb1
mkfs.xfs -f /dev/xvdb2 && mount /dev/xvdb2 /mnt

Two things to note:

• 1024 above is the size in blocks (82 is Linux swap partition type). It seems that for different instances block sizes can be different (just like device names). So experiment first or calculate what is right for you based on sfdisk output.
• mkfs.xfs normally takes seconds. mkfs.ext4 may take half an hour (on a 1TB volume). YMMV depending on the filesystem you choose.