Single write region

Availability impact
Clients will redirect reads to other regions.Without service-manages failover, clients will experience write availability loss, until write availability is restored automatically when the outage ends. With service-managed failover clients will experience write availability loss until the services manages a failover to a new write region selected according to your preferences.
Durability impact
If strong consistency level is not selected, some data may not have been replicated to the remaining active regions. This depends on the consistency level selected as described in this section. If the affected region suffers permanent data loss, unreplicated data may be lost.
Write region outage
What to do
During the outage, ensure that there are enough provisioned RUs in the remaining regions to support read traffic.Do not trigger a manual failover during the outage, as it will not succeed. When the outage is over, re-adjust provisioned RUs as appropriate. Accounts using SQL APIs may also recover the non-replicated data in the failed region from your conflicts feed.