Current builds of Exchange Server 2013 (which is up to CU6 at this time) have a bug in the Get-MailboxDatabaseCopy cmdlet that may cause an incorrect value to be returned for the activation preference of a database copy.
The bug is harmless to the operation of the database availability group (it will still use the correct activation preference values), but if you’re relying on Get-MailboxDatabaseCopy to return those values in a script, or just during general admin, then you may be misled by the bug.
Here’s an example. In this case I’ve used Set-MailboxDatabaseCopy to set each copy of the database DB02 to an activation preference of 4.
[PS] C:\>Set-MailboxDatabaseCopy DB02\MELEX1 -ActivationPreference 4 [PS] C:\>Set-MailboxDatabaseCopy DB02\MELEX2 -ActivationPreference 4 [PS] C:\>Set-MailboxDatabaseCopy DB02\SYDEX1 -ActivationPreference 4 [PS] C:\>Set-MailboxDatabaseCopy DB02\SYDEX2 -ActivationPreference 4
There are no warnings or other indications that it isn’t working, and Get-MailboxDatabaseCopyStatus shows me a result like this.
[PS] C:\>Get-MailboxDatabaseCopyStatus DB02 | select name,status,activationpreference | ft -auto Name Status ActivationPreference ---- ------ -------------------- DB02\MELEX1 Healthy 4 DB02\MELEX2 Healthy 4 DB02\SYDEX2 Mounted 4 DB02\SYDEX1 Healthy 4
Activation preference values are unique for each copy of a database, you can’t have an AP of 4 for every copy. And in this case I don’t, it is just the bug in the cmdlet.
If I use Get-MailboxDatabase to query the AP instead I see the correct values.
[PS] C:\>Get-MailboxDatabase DB02 | Select -expandproperty:ActivationPreference Key Value --- ----- SYDEX2 1 MELEX1 2 MELEX2 3 SYDEX1 4
And if I use the RedistributeActiveDatabases.ps1 script to rebalance the DAG it uses the correct AP values in doing so (truncated output here just to demonstrate the point).
----------------------- Starting Database Moves ----------------------- Considering move of 'DB02' from 'SYDEX2' (AP = 3) to 'MELEX1' (AP = 1)... Database 'DB02' successfully moved from 'SYDEX2' to 'melex1'. ServerName ActiveDbs PassiveDbs ---------- --------- ---------- MELEX1 2 2 MELEX2 1 3 SYDEX1 1 3 SYDEX2 0 4 `n ---------------- Summary of Moves ---------------- Successfully moved : 1 Moved to less preferred : 0 Failed to move : 0 Not moved : 3 DbName : DB02 ActiveOnPreferenceAtStart : 3 ActiveServerAtStart : SYDEX2 ActiveOnPreferenceAtEnd : 1 ActiveServerAtEnd : melex1 IsOnMostPreferredCopy : True MoveStatus : MoveSucceeded
We can expect a fix for this bug in a future update, most likely Cumulative Update 8 at the earliest. It isn’t a serious issue, as long as you’re aware of it and use the Get-MailboxDatabase cmdlet to verify your AP values are correct.
Thanks to Abram Jackson from the Microsoft Exchange PG for confirming this bug and providing the workaround.
This article Get-MailboxDatabaseCopyStatus Displays Incorrect Activation Preference Value is © 2014 ExchangeServerPro.com
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