I have exchange 2013 2 MBX in DAG environment with 4 DBs one of the DAG nodes encountered the trust relationship issue and unfortunately most of the activated DBs was reside on it.
the steps that I have took was performing a dial tone recovery as the below steps:
created a new dial tone DBs (DTDB1,DTDB2,DTDB3)
Rehomed the users from DBs to corresponding Dial tone DBs except 2 DBs I homed them in the one dial tone DB :(
Get-Mailbox -Database DB1 | Set-Mailbox -Database DTDB1
Get-Mailbox -Database DB2 | Set-Mailbox -Database DTDB2
Get-Mailbox -Database DB3 | Set-Mailbox -Database DTDB3
Get-Mailbox -Database DB4 | Set-Mailbox -Database DTDB3
Fixed trust relation issues and the lost server become alive again and all replications are working properly.
before going to the production I tested on my lab to rehome the users back to the original DBs but have 2 issues.
Get-Mailbox -Database DTDB1 | Set-Mailbox -Database DB1
Get-Mailbox -Database DTDB2 | Set-Mailbox -Database DB2
Get-Mailbox -Database DTDB3 | Set-Mailbox -Database DB3
Get-Mailbox -Database DTDB3 | Set-Mailbox -Database DB4
1. the 2 DBs that I homed on the same dial tone DB some of them encountered an error message on OWA (your account has been disabled) because that users are homed backed to the wrong DB.
2. the messages that sent and received during dial tone period how can I merge them with the original database.