Exchange Server 2010 Mailboxes and the ServerName Attribute

Tom asks about a situation where mailboxes on an Exchange Server 2010 database that is no longer part of a database availability group are showing different values for the ServerName attribute.

I’ve had this question a few times before so I wanted to demonstrate the behaviour of Exchange when it comes to that ServerName attribute.

To begin with, I have a database MB-HO-01 in my DAG that is active on server HO-EX2010-MB1. If I retrieve a count of mailboxes grouped by ServerName, then this is the result.

[PS] C:>Get-Mailbox -Database MB-HO-01 | Group-Object -Property:ServerName | Select Name,Count | ft -auto

Name          Count
----          -----
ho-ex2010-mb1   140

So, of the 140 mailboxes on the database they all have a ServerName value of “ho-ex2010-mb1”.

Next, I move the active database copy to server HO-EX2010-MB2.

[PS] C:>Move-ActiveMailboxDatabase MB-HO-01 -ActivateOnServer HO-EX2010-MB2

Confirm
Are you sure you want to perform this action?
Moving mailbox database "MB-HO-01" from server "HO-EX2010-MB1.exchangeserverpro.net" to server
"HO-EX2010-MB2.exchangeserverpro.net".
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [?] Help (default is "Y"): y

Identity        ActiveServerAtS ActiveServerAtE Status     NumberOfLogsLost   RecoveryPoint MountStatus MountStatus
                tart            nd                                            Objective     AtMoveStart AtMoveEnd
--------        --------------- --------------- ------     ----------------   ------------- ----------- -----------
MB-HO-01        ho-ex2010-mb1   ho-ex2010-mb2   Succeeded  0                  5/18/2014 ... Mounted     Mounted

Then, I create a new mailbox on the database MB-HO-01.

[PS] C:>New-Mailbox "Test1" -Shared -Database MB-HO-01

Name                      Alias                ServerName       ProhibitSendQuota
----                      -----                ----------       -----------------
Test1                     Test1                ho-ex2010-mb2    unlimited

As you can see the ServerName attribute matches the name of the server where the database is currently active.

Another look at mailboxes on MB-HO-01 grouped by server name now shows a different result:

[PS] C:>Get-Mailbox -Database MB-HO-01 | Group-Object -Property:ServerName | Select Name,Count | ft -auto

Name          Count
----          -----
ho-ex2010-mb1   140
ho-ex2010-mb2     1

I then move the active database copy back to HO-EX2010-MB1.

[PS] C:>Move-ActiveMailboxDatabase MB-HO-01 -ActivateOnServer HO-EX2010-MB1

Confirm
Are you sure you want to perform this action?
Moving mailbox database "MB-HO-01" from server "HO-EX2010-MB2.exchangeserverpro.net" to server
"HO-EX2010-MB1.exchangeserverpro.net".
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [?] Help (default is "Y"): y

Identity        ActiveServerAtS ActiveServerAtE Status     NumberOfLogsLost   RecoveryPoint MountStatus MountStatus
                tart            nd                                            Objective     AtMoveStart AtMoveEnd
--------        --------------- --------------- ------     ----------------   ------------- ----------- -----------
MB-HO-01        ho-ex2010-mb2   ho-ex2010-mb1   Succeeded  0                  5/18/2014 ... Mounted     Mounted

The server name attribute of the new mailbox retains its value of HO-EX2010-MB2.

[PS] C:>Get-Mailbox -Database MB-HO-01 | Group-Object -Property:ServerName | Select Name,Count | ft -auto

Name          Count
----          -----
ho-ex2010-mb1   140
ho-ex2010-mb2     1

As you can see, when a mailbox is created on a database that is part of a DAG the ServerName attribute is assigned a value of the name of the server hosting the active database copy at a time. It would be normal to see a mix of different server names for mailboxes on the same database if the active copy was not strictly maintained on the same DAG member the majority of the time.

Tom’s case takes this a little further – he has removed the DAG and has two standalone mailbox servers now. Even though only one copy of the database exists, some of those mailboxes still show a ServerName value for the *other* server that does not host that database at all. I believe the issue here is simply that the ServerName attribute is not updated even if you remove your DAG and revert to standalone mailbox servers.

This is not a fault or bug, it is just the behaviour of the product.