Multiple write regions
Possibility of temporary write availability loss, analogously to single write region with service-managed failover. The failover of the conflict-resolution region may also cause a loss of write availability if a high number of conflicting writes happen at the time of the outage.
Recently updated data in the failed region may be unavailable in the remaining active regions, depending on the selected consistency level. If the affected region suffers permanent data loss, unreplicated data may be lost.
Any regional outage
What to do
During the outage, ensure that there are enough provisioned RUs in the remaining regions to support additional traffic.When the outage is over, you may re-adjust provisioned RUs as appropriate. If possible, Cosmos DB will automatically recover non-replicated data in the failed region using the configured conflict resolution method for SQL API accounts, and Last Write Wins for accounts using other APIs.