...
However, since these assets are served by edx.org webservers, if many students using low bandwidth connections attempt asset downloads, a large number of available connections are used up for a long period of time by the asset downloads. This situation leaves only a limited number of remaining connections for students taking courses - and has caused the edx.org website to become unresponsive in the past. The workaround for this situation has been to move frequently-requested, mostly large assets out of GridFS and instead serve them from external servers via URLs. This workaround causes locked assets to become unlocked and creates a special, non-standard situation for certain assets. Clearly, a better solution is needed.
A previous wiki page addresses this task - it's here: Assets for split mongo
Plan
The plan is to change edx-platform to serve all static course assets from external storage using external webservers. On course asset upload, the uploaded asset will be uploaded to external storage by the edx-platform and a URL to the asset will be stored instead of storing the asset. On course asset download, the URL to the asset will be served to the client, which will then download the asset from the external storage directly. This change will allow edx.org webservers and their application to dedicate their connections and processing to course content serving and exercise-taking logic instead of asset serving.
...