Embodiments in the present disclosure include systems and methods related to a high-availability architecture for a cloud-based concurrent-access collaboration platform. The disclosed technology relates to an active data center which includes multiple document server instances that handle user requests for concurrently accessing documents. Multiple document server instances are implemented on a single physical server. This architecture uses an instance assignment manager to assign documents to the document server instances, a primary repository to store backup snapshots of the documents, and a datastore to store all changes made to the documents. The disclosed technology also involves a backup data center that can be swapped with the active data center automatically.