Here are the possible reasons that is eating up the disk space in Confluence and how you can check on them

The unnecessary attachments cause

Super large files

This is usually the #1 culprit and will be most effective in reducing the disk space used

What to check

Are there very large large attachments (e.g. >100MB) which are not supposed to be there?

Why it happens

What you can do

Check out the largest attachments in the space and remove them if they are not required

Go to Space Tools > Attachments
Click on the Size header to sort the attachments in decreasing order of size
Review the content to check if they are relevant

You can also inform the Confluence admins to update Attachment Checker to block the undesired file types

Many historical versions

What to check

Are there many historical versions of the very large files?

Why it happens

Sometimes a file may have multiple iterations of revisions during the course of work

What you can do

Remove the historical versions of very large files

Click on the “Attached To” page of the very large attachments
Click on the … button and select Attachments from the dropdown menu to view the list of attachments added to the page
Click on the toggle button beside the filename to see all the versions
If the historical versions are not required, you can click on the corresponding Delete links to remove the file

What to check

Have you emptied the trash in the space?

Why it happens

The default policy is to retain all the deleted files in the trash and nobody ever empty the trash in Confluence.

What you can do

Review the files that are safe to be deleted

Go to Space Tools > Trash
Review the list to check that there are no recently deleted files that need to be restored
Click on Purge All to empty the trash

You can also enable the Retention rules to clear the attachments that have been deleted more than 3 months.

To reduce the overheads of space administration, you may want to share the following guidelines with your fellow Confluence users

Understand the purpose of the space and what type of content should be added inside
- Confluence is used for knowledge sharing and collaboration. It should not be used as their personal backup storage
Delete the historical versions if they are no longer necessary
1. Use a different filename if there is a need to retain that version of the file
Delete those files that are irrelevant or uploaded by accident
Everyone can play a part to flag out or delete outdated content whenever they come across any
Avoid uploading very big files unless necessary
- Segment the content that are permanent and temporary under different pages so that it is easy to do housekeeping
- You can also use labels (e.g. #canDeleteAfter1Year) to denote pages and attachments that can be deleted

The number of files will definitely grow over time, so it is not realistic to expect users to housekeep to the same level
The purpose of housekeeping is not to create extra work for the space admins
- There is no need to review each and every file in the Confluence space
  - There is little value to spend 1 hour to delete 60 files to free up 17MB of disk space
- If it is painful to do housekeeping, users may be discouraged to use Confluence to collaborate
The purpose of the review is to identify misuse and excessive disk space consumption that leads to wastage.
By doing a review, it helps to check that people are using Confluence in the right manner
We recommend to do a review every 6 months or 1 year so that it is manageable