Confluence site backups/exports are failing with a storage error

Issue Summary

Confluence site backups/exports are failing with a storage error.

Steps to Reproduce

1. Navigate to the Backup Manager menu in Confluence.
2. Try to create a Confluence site export.
3. The export will fail with a storage error.

Expected Results

The Confluence site export should happen without any errors.

Actual Results

The below error is thrown on the screen.

Export error 
/opt/micros/data/ExportRunnerImple-<code>: No space left on device
But don't worry, well fix it for you!
You just need to contact Atlassian support and paste in this error message, timestamp and your instance details.
Timestamp: <timestamp> 

Workaround

• Please raise a ticket with Atlassian Support at https://support.atlassian.com/contact and we can help.