Exchange DAG - Updating from Local Copy
Let's assume that there are two Datacenters - Production and DR. There are two Exchange servers in Production and one in DR Datacenter - they all are in the same Database Availability Group (DAG). I have newly installed DR-EX02 in the DR Datacenter and wanted to update / seed the Databases (DB) from the local copy in the same site (DR-EX01) to make it quicker and in some cases to save the cost.
I have listed the Datacenters and servers below.
DC1 - Domain Controller
EX01 - Exchange Server
EX02 - Exchange Server
DR-DC1 - Domain Controller
DR-EX01 - Exchange Server
DR-EX02 - Exchange Server
The following are the Databases (DB) in a single DAG that's spanned across to DR Datacenter.
DB01 - Active on EX01
DB02 - Active on EX01
I have shown them all in below diagram.
Follow the below steps to update / seed from local copy (DR-EX01). You must use Exchange Management Shell. Unfortunately, Exchange Admin Center (EAC) doesn't give you an option to choose the source server for seeding - it always seeds from the active copy, in this case EX01 in Production Datacenter.
Add DR-EX02 to the same DAG as other servers
Open Exchange Management Shell
Run the below cmdlet to add a copy of DB01 database on DR-EX02. It just adds a copy and does not copy / update the DB.
Add-MailboxDatabaseCopy -Identity DB01 -MailboxServer DR-EX02 -ActivationPreference 4 -SeedingPostponed
Wait for few minutes for the DB to be in Suspended status, then run below cmdlet
Update-MailboxDatabaseCopy DB01\DR-EX02 -SourceServer DR-EX01 -DeleteExistingFiles -Confirm:$false
Please note that above cmdlet will Delete existing files for the DB on DR-EX02. If you do not want them to be deleted, do not use -DeleteExistingFiles
Depending on the size of the DB it could take few minutes or hours to complete the seeding.
I hope you found this useful.