Introduced in GitLab Enterprise Edition 8.12.
Repositories within your GitLab instance can grow quickly, especially if you are using LFS. Their size can grow exponentially and eat up your storage device quite quickly.
In order to avoid this from happening, you can set a hard limit for your repositories' size. This limit can be set globally, per group, or per project, with per project limits taking the highest priority.
Only a GitLab administrator can set those limits. Setting the limit to 0 means there are no restrictions.
These settings can be found within each project's settings, in a group's settings and in the Application Settings area for the global value (/admin/application_settings).
When a project has reached its size limit, you will not be able to push to it, create a new merge request, or merge existing ones. You will still be able to create new issues, and clone the project though.
Uploading LFS objects will also be denied.
In order to lift these restrictions, the administrator of the GitLab instance needs to increase the limit on the particular project that exceeded it.
The first push of a new project cannot be checked for size as of now, so the first push will allow you to upload more than the limit dictates, but every subsequent push will be denied.
LFS objects, however, can be checked on first push and will be rejected if the sum of their sizes exceeds the maximum allowed repository size.