Storage.
WHAT COUNTS
Website files Databases Email Backups on the account Logs Cache
WHAT USUALLY FILLS IT
Backups generated and never removed Mailboxes, particularly Trash and Junk Uploaded media, especially video Log files Old site copies
THE BACKUP POINT
The most common cause by a wide margin.
Several full backups from different dates, sitting in the account.
THE SYMPTOM OF A FULL ACCOUNT
Uploads fail Email stops being delivered The site may stop working Databases may refuse writes
That second one causes the most damage. Mail is rejected and senders receive failures.
WHAT TO DO
cPanel Disk Usage, sorted by size. Work down from the largest.
WHAT TO CHECK MONTHLY
Disk usage, before it becomes urgent.
A full account fails suddenly and confusingly.
