We have installed exchange 2013 since one year now ,our setup is consist of 6 exchange servers hosted on hyper-V 2012 windows server .
Four servers for Databases and CAS in the primary site and the other two in disaster recovery site "One for mailboxes and one for CAS" .
We have configured DAG and each exchange mailbox server is holding database copy "either active or passive " .
For high availability ,We have configured six different databases. Five databases are part of DAG configuration and one database is used for GFI mail archiving "Stand Alone" ,The five databases which is part of DAG configurations have two copies on exchange DAG members .
To distribute the load between servers ,We usually segregate the databases between DAG members where each mailbox server in the primary site supposed to have three databases .
DB01,DB02,DB03 are hosted on exchange MB01 and DB04,DB05 and GFIMAilarchive are hosted on exchange MB02
the third exchange MB03 is acting as passive and holding database copies of DB01......DB05 .
DAG is not stable because databases keep moving automatically between DAG members ,
Example :
After activating database copies of DB01,DB02 and DB03 to be hosted on exchange MB02 .Databases every day after midnight "Around 03:28AM" are moved automatically to MB01 or MB03 and Same is happening with MB01 where databases are failed to the first available exchange mailbox server that hold a valid database copy .
I have many errors and warring on the applications logs .The latest error which i found today on MB02 :-
At '3/4/2014 3:28:12 AM' the Exchange store database 'DB01' copy on this server timed out on periodic status check. For more details about the failure, consult the Event log on the server for other storage and "ExchangeStoreDb" events. The passive database copy will retry to mount as passive.
The even ID is 165 under applications logs
our storage is EMC VN5300 and DB LUNs is assigned directly to exchange MB virtual machine .We don't have SAN switch ,Our configuration is back to back where host server is connected direct to the storage through fiber "Qlogic HBA"
Please help as we are suffering since one year