Exchange 2016 (database priority/activation versus maintenance mode) - Scenario

Question

Hello,

Looking for feedback on a scenario shown below. I believe there are two options to choose from (maybe more), so any feedback or advice would be greatly appreciated.

Task:
Mailbox migration - Old Site to new Site (multi-Datacenter)

New Exchange Environment:
Site A & Site B with multiple database copies active in each site to support site resilience.

Goal:
To migrate mailboxes to the new exchange environment, but temporarily keep mailboxes only active on databases in Site A.

Thoughts:
As I understand it, there are really two ways to address this.

1. Place Exchange servers in Site B in maintenance mode so the database copies in Site A go ACTIVE. I believe the database copies will continue to sync and stay up to date in Site B even though Site B is in maintenance mode, but would like to confirm if possible.
2. Manually ACTIVATE the databases with lowest priority in Site A and run the following command to prevent them from becoming ACTIVE again in Site B as Site B contains some databases with higher priority for activation.

Set-MailboxServer SITE-B-SERVER -DatabaseCopyAutoActivationPolicy Blocked

I understand that the environment would have less copies resulting in higher risk, but what might be a better option (1 or 2) or maybe a 3rd option? Site B may be cold for a month or two where we would NOT want to run active mailboxes out of that site?

Thanks again for any feedback provided.

CWT

Answer 1

Depends :)
If you do not want Site B servers used at all for client access, transport redundancy, holding quorum or database activation, then use option 1. ( and make sure the servers get marked down in any load balancing solution.)
If you place a server in maint mode, and suspend database copying, then the servers in Site B will not keep up to date with the servers in Site A as far as log replay:
https://learn.microsoft.com/en-us/powershell/module/exchange/suspend-mailboxdatabasecopy?view=exchange-ps

If you only want to block automatic activation of the database copies but allow client access and the DAG to function otherwise - and log shipping, choose the second option and simply block activation on the Site B servers.

I like option 2

Answer 2

@CWT
From this article we can know that one of the functions of maintenance mode is to stop auto activation. If you just want to prevent mailbox copy in new site from activation, I also suggest you to prevent database and server from activation directly.

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Answer 3

Thank you both very much for your input. Much appreciated.

CWT