Inode is a Linux (and other Unix-like) data structure used to keep information about the files, folders, emails, code, and everything else on your server. The number of inodes corresponds the number of files and folders you have. Therefore, the more files and folders you have on your server, the higher your inode usage will be.
Keep in mind that inode usage differs from disk space usage (KB, MB, GB). For example, let’s suppose you are using 30 / 50GB of disk space on your server. This would represent your disk space usage. However, if you have hundreds of thousands of small files within that 30 /50 GB, that could result in high inode usage, which could negatively affect the performance of your server.
What happens if you hit the inode limit?
We have two limits. The first is soft limit (shown in the cPanel), meaning the account will still function but you’ll have a warning message in your cPanel.
At this point in time there isn’t a need to panic, but it should serve as a reminder to start doing some basic website “house keeping” to reduce the limit. As stated above, this may include deleting some old files and/or emails.
Once you hit the hard limit (+50,000 of current limit) the account will cease to function. Meaning you’ll no longer be able to upload new files, receive emails, etc. until you bring that number down.