As I found out, a little known “feature” of PHP is that a custom location can be set for session files that isn’t automatically cleared by a cron job. If the PHP application is crappy enough cough cough, it won’t clear them on its own but blindly trust PHP’s garbage collection to do so, which is often times disabled by default – at least on Debian systems. After a while these session files pile up until all inodes are used up and the application fails. Read more about this here and here.
Here’s how to solve it:
Create a shell script,
find /var/www -type f -name "sess_*" -delete
Make it executable:
chmod +x clearTempFiles.sh
Create a cronjob. In this example,
clearTempFile.sh is set to run every Sunday at 4AM.
0 4 * * 0 /home/yourname/clearTempFiles.sh
After running this script once, my inode usage dropped from nearly 100% to 20% and over 100k inodes were freed. Alternatively, you could set the