Inodes in Linux system usually describes the number of files you have in the server. Some web hosting providers set up a limitation of inodes on your hosting server. For some reasons, depending on which web application you are using, the number of inodes will grow up to an incredible number. The extra file may include emails, emails attachments, some web cache files that generated by the web application and so on.

To determine the inodes usage on your server, you can use this command to extract the inodes details for each directory. If you cannot access the hosting server physically, you can set up a ssh connection to your server.

echo "Inode usage for: $(pwd)" ; for d in `find -maxdepth 1 -type d |cut -d\/ -f2 |grep -xv . |sort`; do c=$(find $d |wc -l) ; printf "$c\t\t- $d\n" ; done ; printf "Total: \t\t$(find $(pwd) | wc -l)\n"

Hope this can solve your high inodes usage problem in your server :)