Hard File Limits

A while ago, we ran up against a hard file limit on our storage server. Within the main images directory, we subdivide our folders for every user. Well, it turns out that on the ext3 filesystem, there is a hard limit of 32k folders within a folder. So when our 32001th user signed up, they were welcomed by not being able to upload any content to their nonexistent user folder.

So there we were…

Several calls to our hosting provider Rackspace yielded no elegant solution where we could simply reconfigure the limit. If we wanted to continue on with our file structure the way it was, we would need to migrate our data off the server, reformat the filesystem to xfs, and migrate back on. That would take us down for close to 36 hours. Needless to say that was not an option.

The other option was to quietly close registration, and start a mad dash to implement programmatic partitioning. We created 5 folders next to our root user content folder, numbered them 2-5, and assigned current users the partition of 1. New users would be assigned a randomly generated number at registration. Then we wrote a few quick utility methods to determine which user belonged to which partition and began the quickest rewrite of file upload system the world has ever seen.

Downtime : 0

In retrospect, someone (me) should have taken a scrutinizing look at the characteristics of the filesystem that would be responsible for storing all of our users' content.

Lesson learned, the hard way.

May 10th, 2009