Exchange 2013 DAG FailedAndSuspended

Hey guys,

This week I got a new customer with a funny interesting problem in his Exchange 2013 environments,
The new customer suffered from inactive & active availability with regards to Exchange services, some different IT integration company provided them support and maintenance, due to some internal reasons they have decided to join our IT integration and strengthen their productions services,the first task they ask me to check is the Exchange environments which was mostly down, unavailable and painful point.
I noticed that they have two Exchange servers that configured with DAG service and the witness server is the Active Directory which is OK.
They have three databases that should be synced to the second Exchange, While going over the DAG settings I have noticed that there are unclear events in the event viewer like the following one


The indexing of mailbox database XXX encountered an unexpected exception. Error details: Microsoft.Exchange.Search.Core.Abstraction.OperationFailedException: The component operation has failed. ---> Microsoft.Exchange.Search.Core.Abstraction.CatalogReseedException: The database '74xxxxx-485c-90cb-xxxxxxxxx(XXX)' needs to be crawled but is not mounted on the preferred active server. Requesting a reseed. at Microsoft.Exchange.Search.Engine.SearchFeedingController.PrepareToCrawl(NotificationsEventSourceInfo ciWatermarkInfo) at Microsoft.Exchange.Search.Engine.SearchFeedingController.DetermineFeederStateAndStartFeeders() at Microsoft.Exchange.Search.Engine.SearchFeedingController.InternalExecutionStart() at Microsoft.Exchange.Search.Core.Common.Executable.InternalExecutionStart(Object state) --- End of inner exception stack trace --- at Microsoft.Exchange.Search.Core.Common.Executable.EndExecute(IAsyncResult asyncResult) at Microsoft.Exchange.Search.Engine.SearchRootController.ExecuteComplete(IAsyncResult asyncResult)


I noticed that on server A there are three disks, one of them was 450GB, I decided validating and verifying these settings on the second server and noticed that this DB isn’t syncing to the second Exchange at all, the partition size is just 200GB which is lower then first Exchange, I don’t know why they have configured it like this, in the Exchange Management I got “FailedAndSuspended” status on this DB, therefore I have run the reseeding process, yes it took some time, but once it finish the database syncs perfectly.

I used on this cmdlet in order to verify the “Contentindexstatus”:

Get-MailboxDatabaseCopyStatus * | ft -auto