Amazon EC2: No space left on device

Published on May 04, 2015

So a funny thing happened today at out pre-production environment. I was performing our pre-big-PR deployment when a beautiful error was shown in my terminal:

cannot create X: No space left on device

What?! How could that be possible. I know that our environment don't have a lot of bytes for us to play with but having the storage already full with our database and other services outside this machine just wasn't possible. And I was right.

[email protected]:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1       59G   37G   21G  65% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
udev            2.0G   12K  2.0G   1% /dev
tmpfs           396M  400K  395M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none            2.0G     0  2.0G   0% /run/shm
none            100M     0  100M   0% /run/user

What?! Now I sure don't understand a thing. I was laughing hysterically when my brain just started working as I remembered an old friend: the inode.

[email protected]:~$ df -i
Filesystem      Inodes   IUsed   IFree IUse% Mounted on
/dev/xvda1     3932160 3932160       0  100% /
none            505855       2  505853    1% /sys/fs/cgroup
udev            504558     403  504155    1% /dev
tmpfs           505855     332  505523    1% /run
none            505855       1  505854    1% /run/lock
none            505855       1  505854    1% /run/shm
none            505855       4  505851    1% /run/user

Fk you. Our deploys are made using "isolated" builds. That is, we reinstall pip/bower requirements for every build.** So each build take about ~50k inodes, and we keep some in case some rollback is needed, but of course, keeping two months old builds wasn't needed at all, so I made a script that just deletes builds older than two weeks and our poor thing was happy again.

To search which folder of your server is eating the inode limit, you can run this command:

find . -xdev -type f | cut -d "/" -f 2 | sort | uniq -c | sort -nr

This will show the path name and the inode count, keep going inside dirs to get some detailed input, once found, just delete the files that are causing havok.

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