In this case I recommend you to raise a ticket in our Support Channel: http://support.atlassian.com
This is the guide related to your request: https://confluence.atlassian.com/display/CLOUDKB/How+Much+Disk+Space+is+Being+Used+By+JIRA+and+Confluence+Cloud
However, only the support team have access to the server to help you with this info.
I hope it helps
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