It's important to identify and correct the root issue that caused the high disk/inode usage. Here are some common causes for high disk usage, excessive inode usage, and suggested solutions:

Misconfigured WHM and cPanel backups:

Review the "Backup Configuration" in WHM. Keep fewer backups, or configure the WHM backups to "strictly enforce retention" which will automatically delete the oldest backup when a new one is created.

If the server is keeping more than the specified number of backups, this is generally because an error is happening during the backup that prevents it from completing fully. You can review the backup logs at /usr/local/cpanel/logs/cpbackup using SSH.

Misconfigured CMS backups:

Review the configuration of any backup plugin/extension installed on any website and verify that a reasonable retention policy has been defined. Don't keep all backups indefinitely.

Website configuration:

Some websites that store user-uploaded content store these uploads in the same directory. Over time, this directory can grow to an unmanageable size. Consult your web developer to make sure your website has a mechanism to store uploaded content into different directories.

Misconfigured CMS session/cache files:

If session files are not regularly removed, the directory that sessions are stored in may exhaust server inode limits. Be sure that any cron jobs that remove stale session data are running, and that old sessions are removed on a regular basis.

Excessively large error log files:

An update to one or more websites may be the reason for large error logs. Review any newly generated error log files carefully and correct any coding errors so the log file does not quickly grow to an unmanageable size.

Email spam issues:

Compromised websites or email accounts are commonly abused to send excessive spam that can build in the outgoing email queue until available disk/inodes are exhausted.