3

I'm trying to figure out how to make two Exchange Servers replicate.

My goal is to make that Exchange Mail keeps working even if one of the server fails or is for whatever reason unreachable.

They already talk to each other through AD and as far as I know most things are already replicating, except the Mailbox Databases. If a server goes offline, every Mailbox associated with it's Database becomes inaccessible.

So I did some research and apparently they should use one single Mailbox Database, replicated between them. But here is where the problems begin.

If I got this right I have to create a Database Availability Group, put the two servers in it, and set up a Mailbox Database Copy between them.

The problem is, apparently the Database Availability Group cannot be managed by a server in the group, it has to be a third one (called "DAG Witness")? What the hell.

Is there some way to workaround this? I don't want to have three servers, and to make matters worse the docs say the DAG Witness has to be a Windows Server too.

There must be some way to achieve this without having to rent an entire Data Center.

Improve this question
3
  • They already talk to each other through AD and as far as I know most things are already replicating, except the Mailbox Databases - That's probably an incorrect statement. If you didn't set up any HA then there isn't any HA. If you didn't set up a DAG then there is no DAG. Did you set up a DAG or HA?
    – joeqwerty
    Nov 1, 2018 at 22:49
  • @joeqwerty Neither. As far as I can tell both DCs replicate settings to each other out of the box, including Mailboxes and Exchange Server settings, except the Mailbox Databases. Am I missing something?
    – Havenard
    Nov 1, 2018 at 23:59
  • Mail related attributes of mail enabled objects are replicated as a part of AD replication, but that isn't and doesn't provide any HA for Exchange mailbox databases or mailboxes. You need to configure HA specifically for Exchange.
    – joeqwerty
    Nov 2, 2018 at 1:51

2 Answers 2

Reset to default
4

This description is wrong:

The problem is, apparently the Database Availability Group cannot be managed by a server in the group, it has to be a third one (called "DAG Witness")?

You do need a Witness. However, it doesn't manage anything.

The Witness could be as simple as a share on third server. No extra software is needed. And a dedicated server is not required.

Improve this answer
11
  • But do they have to be in the Domain? And what happens if this file share goes offline? Can it be a Linux Server with Samba?
    – Havenard
    Nov 1, 2018 at 20:23
  • 1
    Yes, it has to be in the domain. If the Witness goes offline and the two Exchange servers are still running, then nothing happens. But if the Witness is offline and one Exchange server goes offline, then the other Exchange server will not automatically bring the databases online.
    – longneck
    Nov 1, 2018 at 20:27
  • 1
    You should read up on how Quorum works in Microsoft Failover Clusters.
    – longneck
    Nov 1, 2018 at 20:28
  • I'm currently trying to figure out how I can get a Linux VM with Samba to do this role, before I go further do you know if it's possible or am I wasting time?
    – Havenard
    Nov 1, 2018 at 20:57
  • Are you trying to give yourself indigestion? Forget it. What's the aversion to using a regular Windows server? You must have one somewhere else already. Even a share on a domain controller would be better than Samba.
    – longneck
    Nov 2, 2018 at 0:55
0

You can configure a DAG with just two servers without a witness server. However, keep in mind that without a witness server, you won't have automatic quorum management for odd-numbered DAGs. For set up a DAG with two Exchange Server, refer this link.

Improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .