In exchange2010 mail system, a DAG is created to support high availability of mailbox database, each db has two copies which are located in mailbox server respectively.
when trying to fall back DB1 to EXC-1A, an error appears below, fail to active DB1 in another server
manually start all the services of exchange application except edgesync in all Exchange Server
Step 1. Check DB1 status, which shows active one is mounted and passive one is healthy
Step 2.check mailbox in DB1 is accessible and working properly by outlook or OWA clients
Step 3. Check exchange service status, some exchange service with automatic attribute is in stop status
Step 4. in normal case, exchange2010 server has 19 automatically running services, all should be in started status, manually start all the services except edgesync
Step 5. Check exchange service status in both exchange servers. Make sure 19 services are started. and fall back database again successfully.
If exchange server is shutdown by cutting off power directly instead of by windows commands, some service of exchange can not start properly next time.
It suggests that shutdown or restart exchange system via windows procedure