Context
- Shared hosting service (Zuver)
- CPanel
- WordPress 5.3
- W3 Total Cache plugin
TDLR
- Website returns Http Error 503 the service is unavailable. Can’t access the WordPress Administration.
- From CPanel, File Usage reached its hard limit (250,000 files)
- From File Manager, removed directory “wp-content/cache”
- File Usage is now way below the threshold
- Able to access WordPress Administration and configure Total Cache, disabled Database Cache and Object Cache
Explanations
On shared hosting service, it is common to have a limitation on the number of files that can be stored on the hard drive. Even though the Disk Usage is far below the limit (disk 15% full), the File Usage limitation can generate serious issues.
On my hosting provider Zuver, the File Usage soft threshold is 200,000 files which will only give warnings. However, if it hits the 250,000 files hard limit, it will run into issues with the website (Http Error 503 the service is unavailable) and the cPanel account.
Basically, the server separates the entire hard drive into nodes, which are used to store files or parts of files. As you can imagine, a node will be a certain size, and there can only be so many nodes that take up all the space on the hard drive.
Because this is a shared hosting service with more than one user on the server, the number of INodes (files) that can be stored per user must be limited, to avoid hitting the server’s INode limit.
Usually, there is no way to increase the File Usage threshold with the hosting provider. Therefore, an investigation is required.
If WordPress uses W3 Total Cache with Database Cache and Object Cache enabled on disk, chances are that this is causing the issue. Also, you can check the tmp folder and the hidden directories.
The quick fix is to delete the folder /wp-content/cache and then access to the WordPress Administration panel to disable Database Cache and Object Cache.
That’s it.