Hi guys.
Long story short:
SITE 1 - domain1
SERVER1: Exchange2013 - with all the roles installed (15 DB's)
SERVER2: Witness server
SITE 2 - child domain
SERVER3: Exchange2013 - with all the roles installed (2 DB's)
We had configured DAG. All the 15 DB's from EXCHANGE2013 in SITE1 were "replicated/synced" thru DAG to EXCHANGE2013 in SITE 2.
2 DB's which are only on EXCHANGE2013 in SITE2 weren't included in this DAG.
Because SITE1 and SITE2 are dislocated and connected to each other with SITE-TO-SITE-VPN (the line between them has some ups and downs) we have decided that we do not wish that databases are activated on EXCHANGE2013 in SITE2 automatically.
The way we have added databases to be synced thru DAG from EX2013-site1 to EX2013-site2:
add-mailboxdatabasecopy "1st DB on EX2013-site1" –mailboxServer "EX2013-site2" –seedingPostponed:$TRUE
Suspend-MailboxDatabaseCopy -Identity "1st DB on EX2013-site1\EX2013-site2" –ActivationOnly
set-mailboxdatabase "1st DB on EX2013-site1" –circularLogging:$TRUE
Dismount-Database -Identity "1st DB on EX2013-site1" –confirm:$false
Mount-Database -Identity "1st DB on EX2013-site1" –confirm:$false
update-mailboxdatabasecopy "1st DB on EX2013-site1\EX2013-site2" –deleteExistingFiles:$TRUE –confirm:$false
set-mailboxdatabase "1st DB on EX2013-site1" –circularLogging:$FALSE
Dismount-Database -Identity "1st DB on EX2013-site1" –confirm:$false
Mount-Database -Identity "1st DB on EX2013-site1" –confirm:$false
We had a downtime (hardware failure) with EXCHANGE2013 in SITE1 and this caused huge problems (which we don't understand) on EXCHANGE2013 SITE2.
Those 2 DB's on EXCHANGE2013 in SITE2 which weren't included in DAG were unable to mount (don't understand why?).
They didn't want to mount with error: that replication service is not running on EXCHANGE2013 SITE1 (due to downtime of that server).
We don't understand why this behaviour happened because those two databases weren't the part of DAG sync.
We had to manually remove every database on exchange2013 SITE2 from DAG sync, and then we were able to mount those 2 DB's.
Can someone please explain why databases which weren't included in DAG did not automatically mount?
With best regards
bostjanc