How to Rebalance Mailbox Databases in an Exchange Server Database Availability Group

Comments

1. 

   Tony 29 Sep 2018 Reply

   Hi Paul. Sorry for the comment on such an old article, but when i try running it i get this

   Sending data to a remote command failed with the following error message: The WinRM client sent a request to the remote
   WS-Management service and got a response saying the request was too large. For more information, see the about_Remote_
   Troubleshooting Help topic.

   I did some gooling, and made a change to the Web.config file for the powershell virtual directory. That makes the script work. https://www.pei.com/2015/10/windows-server-management-request-too-large/
   But then when i open Powershell for exchange again, it spits out all kinds of errors that it cant connect to the other servers because too many requests, etc..
   Unless i have to make this change on all servers. I just wanted to verify that this wont break anything else as far as you know.

2. 

   Great H 23 May 2017 Reply

   Thanks Paul sincerely, every issues can be resolved after reading your articles instead of open case to Microsoft and waste a lot of time, truely expert.

3. 

   egemen 25 Apr 2017 Reply

   Hello Paul,

   I run the script without any issue but even after the databases move to primary one, they instantly return their first state what could cause this issue?

   Regards,

   1. 

      Paul Cunningham 25 Apr 2017 Reply

      You’ll need to look at your event log to see what is being logged when the active database copies are moving.

4. 

   Felice Gioino 2 Aug 2016 Reply

   Is it possible to balance DB’s by DAG?

5. 

   Mike 28 Apr 2016 Reply

   Hi, Is it safe to copy database.edb and the logs from passive database member without dismounting the database? I wanted to manually copy the db from HQ to DR site and synchronize it as a dag member.

   Thank you.

   1. 

      Mike Walker 9 Sep 2016 Reply

      Negative! Never do anything directly with database/log files while the database is still mounted. There are many sites documenting how to do manual seeds by copying/restoring the database, but all require at least a brief outage to dismount and make the database consistent.

      Another way is to create new databases with the DAG config you want and then move all existing mailboxes to them, so the DAG synch happens at the same time as the moves.

6. 

   Adams Toomer 15 Apr 2016 Reply

   *What if you actually WANT to activate them by their second preference, for maintenance on storage, is there a command to do so?

7. 

   Adams Toomer 15 Apr 2016 Reply

   What you actually WANT to activate them by their second preference, for maintenance on storage, is there a command to do so?

8. 

   Stefan 9 Mar 2016 Reply

   It seems that this script no longer works after CU11 which I think has to do with RPS proxying. Is there a workaround for CU11 to use this script? From what I have read, CU12 will restore RPS original functionality so this may be moot.

   1. 

      Paul Cunningham 9 Mar 2016 Reply

      Wouldn’t surprise me to hear that CU11 broke it. I don’t know if any fix, and CU12 is probably going to be released this month since the last update was in December.

9. 

   sanju 19 Feb 2016 Reply

   For me it never works

   S] D:Exchange Serverv15Scripts>.RedistributeActiveDatabases.ps1 -DagName DAG01 -BalanceDbsByActivationPreference

   annot convert value “DAG01″ to type
   Microsoft.Exchange.Data.Directory.SystemConfiguration.DatabaseAvailabilityGroup”. Error: “Cannot convert the
   DAG01” value of type “Deserialized.Microsoft.Exchange.Data.Directory.SystemConfiguration.DatabaseAvailabilityGroup”
   o type “Microsoft.Exchange.Data.Directory.SystemConfiguration.DatabaseAvailabilityGroup”.”
   t D:Exchange Serverv15ScriptsRedistributeActiveDatabases.ps1:2801 char:3
   $script:dag = Get-DatabaseAvailabilityGroup $DagName -Status
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   + CategoryInfo : MetadataError: (:) [], ArgumentTransformationMetadataException
   + FullyQualifiedErrorId : RuntimeException

   Log-Error : [02:40:33.145 UTC] Could not find DAG matching ‘DAG01’!
   t D:Exchange Serverv15ScriptsRedistributeActiveDatabases.ps1:2806 char:3
   Log-Error ($RedistributeActiveDatabases_LocalizedStrings.res_0089 -f $DagName) …
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   + CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException
   + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,Log-Error

   When i run the Get-DatabaseAvailabilityGroup I see Correct DAG Names. I have removed the Server names here for example

   [PS] D:Exchange Serverv15Scripts>Get-DatabaseAvailabilityGroup

   Name Member Servers Operational Servers
   —- ————– ——————-
   DAG01
   DAG02
   DAG03
   DAG04

   I am 100 percent Sure DAG name is correct. I am on exchange 2013 CU8

   1. 

      Paul Cunningham 19 Feb 2016 Reply

      Are you doing this in the Exchange Management Shell?

      1. 

         Will 20 Aug 2016 Reply

         I had the same issue when I was using Powershell ISE with Exchange snap-in. Run this in EMS and it worked. Thanks Paul.

10. 

    Gareth Hillary 14 Dec 2015 Reply

    This article looks like exactly what we need but when I try to go and run it I fall at the first hurdle.

    We are using Exchange 2013 so the scripts are in a slightly different folder to the syntax however I have edited it to reflect the appropriate folder, V15 instead of 14.

    I get the following output, please can you tell me where I am going wrong:

    [PS] C:\>C:Program FilesMicrosoftExchange ServerV15Scripts>.RedistributeActiveDatabases.ps1 -DagName DAG -ShowData
    base DistributionByServer | ft
    C:Program : The term ‘C:Program’ is not recognized as the name of a cmdlet, function, script file, or operable
    program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
    At line:1 char:1
    + C:Program FilesMicrosoftExchange ServerV15Scripts>.RedistributeActiveDatab …
    + ~~~~~~~~~~
    + CategoryInfo : ObjectNotFound: (C:Program:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException

    1. 

       Gareth Hillary 14 Dec 2015 Reply

       I am a pillock – I have realised how to execute the script. Navigate to the folder first via changing directory from the command line.

       Doh!

11. 

    Robban 15 Oct 2015 Reply

    Hi

    I upgraded to CU10 and this wonderful script stopped working. On my still CU7 it works.
    Anyone noticed this?

    Errro:
    “Cannot process argument transformation on parameter ‘Identity’. Cannot convert value “DATABASENAME” to type “Microsoft.Exchan
    ge.Configuration.Tasks.DatabaseCopyIdParameter”. Error: “Cannot convert hashtable to an object of the following type: M
    icrosoft.Exchange.Configuration.Tasks.DatabaseCopyIdParameter. Hashtable-to-Object conversion is not supported in restr
    icted language mode or a Data section.”
    WARNING: [08:51:27.449 UTC] Cannot bind argument to parameter ‘mdb’ because it is null.Cannot process argument
    transformation on parameter ‘Identity’. Cannot convert value DATABASENAME” to type

    Regards Robban

12. 

    Greg 7 Sep 2015 Reply

    Are there any ramifications on scheduling this script to run periodically/on startup?

    1. 

       Paul Cunningham 7 Sep 2015 Reply

       I wouldn’t run it on startup, that’s not the right time to be doing a DAG rebalance.

       Some people choose to schedule it to run just prior to their backups, if the backups depend on certain database copies being active. Others might run it nightly or weekly depending on how neat and tidy they like things to be.

       Personally I would just run it manually after completing any maintenance.

13. 

    David 23 Feb 2015 Reply

    Ok, check this crazy huge command here:

    I have not tested yet.

    It is supposed to:

    1. Check in the SERVER1, which MailboxDatabases are mounted on it
    2. It lists all MailBoxDatabases from SERVER1 where the ActivationPreference is 2
    3. Displays info about which ones will be moved to the ActivationPreference2 Server where
    4. Ignore the ones that already are on the AP2 Server.

    Get-MailboxDatabase -Server SERVER1 | Where {$_.ServerName -eq “SERVER1”} | Sort Name | ForEach {$db=$_.Name; $xNow=$_.Server.Name ;$dbown=$_.ActivationPreference| Where {$_.Value -eq 2}; Write-Host $db “on” $xNow “Move to” $dbOwn.Key -NoNewLine; If ( $xNow -ne $dbOwn.Key){Write-host “Already On AP 2″ -ForegroundColor Red} {Write-Host ” Moving to” -ForegroundColor Blue; Move-ActiveMailboxDatabase $db – ActivateOnServer $dbOwn.key -confirm:$True} Else {Write-Host ” OK” -ForegroundColor Green}}

    1. 

       Paul Cunningham 23 Feb 2015 Reply

       Ok. Good luck with your testing?

       1. 

          David 26 Feb 2015 Reply

          Ok, with a few tweaks here and there, this is the final ‘WORKING!’ version:

          Move All Databases From One Server to its Activation Preference 2

          Get-MailboxDatabase -Server SERVER1| Where {$_.ServerName -eq “SERVER1”} | Sort Name | ForEach {$db=$_.Name; $xNow=$_.Server.Name ;$dbown=$_.ActivationPreference | Where {$_.Value -eq 2}; Write-Host $db “on” $xNow “Will be moved to” $dbOwn.Key -NoNewLine; If ( $xNow -ne $dbOwn.Key){Write-host ” >>> Moving…” -ForegroundColor Red; Move-ActiveMailboxDatabase $db -ActivateOnServer $dbOwn.key -confirm:$False} Else {Write-Host ” – Already on Activation Preference 2″ -ForegroundColor Green}}

          1. 

             Paul Cunningham 27 Feb 2015 Reply

             Gigantic PowerShell one-liners are messy and difficult to read and understand. Why not write it as a script instead? You’ll thank yourself later.

14. 

    David 23 Feb 2015 Reply

    Hello, Paul.

    I would like to run a script or command line cmdlet, that could move all active mailbox databases from an specific server to the server whose activation preference is 2.

15. 

    Gary 30 Apr 2014 Reply

    How would you script moving all databases to a specific server in the DAG instead of the preferred server? For instance, maintenance will be occurring on server 1 in the DAG so in preparation you move all databases to be mounted on server 2 in the DAG.

    1. 

       Paul Cunningham 30 Apr 2014 Reply

       Use the start/stop DAG maintenance scripts. Demonstrated here:

       https://www.practical365.com/how-to-install-updates-on-exchange-server-2010-database-availability-groups/

16. 

    Edwin 1 Apr 2014 Reply

    What rights does the account that runs the script need? Our script account recently lost domain admin rights, and keeps failing now.

    1. 

       quaaarks 1 Apr 2014 Reply

       These accounts have domain-, schema-, Enterprise-rights

17. 

    quaaarks 28 Mar 2014 Reply

    Hi,
    when I use this script: .RedistributeActiveDatabases.ps1 -DagName dag1 -ShowDatabaseDistributionByServer | ft
    I get following error:

    The operation couldn’t be performed because object ‘dag1’ couldn’t be found on ‘dc.domain.com’.
    + CategoryInfo : NotSpecified: (:) [Get-DatabaseAvailabilityGroup], ManagementObjectNotFoundException
    + FullyQualifiedErrorId : [Server=EXCH1,RequestId=eea7abfb-5a4a-4885-8740-f96617cb4dc7,TimeStamp=27.03.2014 16
    :03:43] D83A179C,Microsoft.Exchange.Management.SystemConfigurationTasks.GetDatabaseAvailabilityGroup
    + PSComputerName : exch1.domain.com

    Log-Error : [16:03:43.628 UTC] Could not find DAG matching ‘dag1’!
    At C:Program FilesMicrosoftExchange ServerV15ScriptsRedistributeActiveDatabases.ps1:2801 char:3
    + Log-Error ($RedistributeActiveDatabases_LocalizedStrings.res_0089 -f $DagName) …

    I receive these errors with Exchange 2013 as well as in Exchange 2010 Environment?
    I would appreciate any help

    1. 

       Rosario 28 Mar 2014 Reply

       Is the name of your DAG really dag1 ?

18. 

    Rosario 1 Mar 2014 Reply

    Paul, thanks, another great article. My question:

    In a DAG none of the databases is mounted on one primary server. They are mounted on the two others. So I would like to redistribute or do a manual switch over, but before doing that, I would ask WHY were they mounted on the other two servers leaving that one server only with copies an no active DB?

    So is there a means to know the reason of this switch over? No hardware failure on that server, no Error entries in the Event Viewer. Where else should I investigate?

    Thanks a lot, Rosario

    1. 

       Paul Cunningham 1 Mar 2014 Reply

       Switchovers and failovers are all logged in event logs. You can drill down into the Applications and Services Logs in event viewer to investigate.

       1. 

          Rosario 6 Mar 2014 Reply

          Thanks, I found the Event-Viewer entries and would like to mention them here for reference.

          On the faulty server have a look at Event-Viewer->Applications and Services Logs->Microsoft->Exchange->HighAvailability and same path->MailboxDatabaseFailureItems

19. 

    James Slack 11 Jan 2014 Reply

    Hi Paul,

    Is there a way to mount a DB on a specific server in a DAG when it is currently mounted on a different server in that DAG?

    We have 12 DBs and 2 servers (ignoring DR). Say I wish to mount only DB7 on DB2 instead of DB1 – how would I do this?

    The reason I ask is that we get some issues when we have to reboot one of the DAG servers. The DBs should all fail over to the other server, but sometimes one or two get stuck in limbo. This makes the other server take 19 minutes (due exchange services) to boot and those DBs that dont fail over are stuck offline until it comes back. I do the reboot correctly, stopping services etc. first.

    If I can dismount DBs one at a time and mount them on the server I desire, it will be a lot better.

    I believe the mount-database command will just mount the DB in the same place.

    Thanks

    1. 

       James Slack 11 Jan 2014 Reply

       Typo sorry “mount only DB7 on Server2 instead of Server1 – how would I do this?” – been one of those days

       1. 

          Paul Cunningham 12 Jan 2014 Reply

          For starters, you’ll avoid all this trouble if you place the DAG member in maintenance mode before you reboot it. Example here:

          https://www.practical365.com/how-to-install-updates-on-exchange-server-2010-database-availability-groups

          (refer to the parts on using StartDagServerMaintenance.ps1 and StopDagServerMaintenance.ps1)

          And just to be clear why this is encouraged:
          https://www.practical365.com/bother-running-dag-server-maintenance-mode-scripts/

          To answer your question, yes you can make any single database copy active on a DAG member without using this rebalance script. You simply do a manual switchover:

          http://technet.microsoft.com/en-us/library/dd298068(v=exchg.141).aspx

          1. 

             James Slack 13 Jan 2014 Reply

             Awesome, Thanks Paul.

             Sadly we updated to 2010 from 2003 and I had no in work training and outside of work was busy with other exams. This means most of the things that are different will remain unknown until you find something by chance (usually the hard way).

             This info is exactly what I needed, thank you.

             Time for me to get learning 2010… probably will have that down just in time to go to 2013.

          2. 

             Paul Cunningham 14 Jan 2014 Reply

             A lot of what you’ll learn for 2010 is still relevant in 2013 anyway, so hit it hard and you’ll be better off in the long run. Really it was the 2003 -> 2007/2010 jump that was the biggest in terms of new stuff to learn.

             There’s some free video training here if you or your team mates need somewhere to start:
             https://www.practical365.com/exchange-2010-free-training-videos/

20. 

    Jetty 13 Dec 2013 Reply

    Question – I am not an exchange admin and am working my way through some Exchange items and would like to understand this better. What would happen in the event of a failure if the active database is mounted on the server with the activation preference of 2?

    1. 

       Paul Cunningham 13 Dec 2013 Reply

       In a failure situation a process called Best Copy Selection evaluates a number of factors and that is how the database copy to attempt to bring online is chosen. Activation preference is one of those factors but it is not the only one.

       If you’re asking if its possible that db copy AP=1 could come online, yes that is possible, if Best Copy Selection chooses that copy.

21. 

    Joe Hardy 15 Nov 2013 Reply

    What kind of impact does this have on outlook clients in a 24/7/365 shop? Is there a default level of availability this script uses? ie: “none” – “best availibility”
    Wondering if end users will see any performance hits or disconnects in outlook if we run this cmdlet / script.
    Thanks,
    Joe

    1. 

       Paul Cunningham 17 Nov 2013 Reply

       Good question. I think it honors the setting on the database, but a quick scan through the script code didn’t find where that might be controlled.

       There’s always a risk even during a planned switchover that something will go wrong of course.

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23. 

    Wayne 14 Jun 2013 Reply

    Hi Paul

    What if i have 3 servers in single DAG (All roles installed on each) 2 are active/passive and 3rd is just passive , how do i make sure that the DB’s end up back on the original place and leave the 3rd as passive?

    1. 

       Paul Cunningham 14 Jun 2013 Reply

       There are no active/passive servers in a DAG. There are only active database copies and passive database copies.

       If you want to control which database copy becomes active when the rebalancing script is run as shown above, then you would set that database copy’s activation preference to 1.

24. 

    Christian 27 Apr 2013 Reply

    Hi Paul,
    Do you know a way to include an email report the result of the command RedistributeActiveDatabases.ps1 -DagName DAG -BalanceDbsBy ActivationPreference in the script?

    1. 

       Jamille 5 Jun 2013 Reply

       Here’s a script to run a dag rebalance and to email you the results. You will have to change the variables below the main comments to suit your environment

       Edit: removed

       1. 

          Paul Cunningham 6 Jun 2013 Reply

          Jamille, I’ve removed your script from the comment. I recommend hosting your script somewhere like the TechNet Script Gallery so you can just link people to it.

          http://gallery.technet.microsoft.com/scriptcenter

          1. 

             Jean-Luc Ch. 15 Oct 2014 Reply

             What a pitty…

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26. 

    Gary H 3 Apr 2013 Reply

    Thanks Paul.. It works like a charm.

    Is there a Script to Automatically Rebalance going forth? or is the only method to run this rebalance script?

    1. 

       Paul Cunningham 3 Apr 2013 Reply

       That is the script, yes.

27. 

    David 20 Mar 2013 Reply

    paul

    can you shed some light…..? IM getting this when i run issue this cmd

    thanks

    .RedistributeActiveDatabases.ps1 -DagName DAG -ShowDatabase
    DistributionByServer | ft

    [PS] C:Program FilesMicrosoftExchange ServerV14scripts>.RedistributeActiveDatabases.ps1 -DagName DAG -ShowDatabase
    DistributionByServer | ft
    C:Program FilesMicrosoftExchange ServerV14scriptsRedistributeActiveDatabases.ps1 : Parameter cannot be processed
    because the parameter name ‘ShowDatabase’ is ambiguous. Possible matches include: -ShowDatabaseCurrentActives -ShowData
    baseDistributionByServer -ShowDatabaseDistributionBySite.
    At line:1 char:34
    + .RedistributeActiveDatabases.ps1 <<<< -DagName DAG -ShowDatabase DistributionByServer | ft
    + CategoryInfo : InvalidArgument: (:) [RedistributeActiveDatabases.ps1], ParameterBindingException
    + FullyQualifiedErrorId : AmbiguousParameter,RedistributeActiveDatabases.ps1

    1. 

       Paul Cunningham 2 Apr 2013 Reply

       -ShowDatabaseDistributionByServer is all on one line. There’s a carriage return that shouldn’t be there.

28. 

    Hein 15 Feb 2013 Reply

    Weird. Can’t see what i am doing wrong. I get this:

    At C:Program FilesMicrosoftExchange ServerV14scriptsRedistributeActiveDatabases.ps1:1928 char:3
    + return $moveSuccessful
    + ~~~~~~~~~~~~~~~~~~~~~~
    Control cannot leave a finally block.
    At C:Program FilesMicrosoftExchange ServerV14scriptsRedistributeActiveDatabases.ps1:2538 char:5
    + return $success
    + ~~~~~~~~~~~~~~~
    Control cannot leave a finally block.
    + CategoryInfo : ParserError: (:) [], ParseException
    + FullyQualifiedErrorId : ControlLeavingFinally

    Hopefully you can shine a light on this and help me out 🙂

    1. 

       Paul Cunningham 15 Feb 2013 Reply

       I’ve never seen that before. Has the script been modified by someone?

    2. 

       David Garcia 15 Aug 2013 Reply

       You need to uninstall Windows Management Framework 3.0 (KB2506146 and KB2506143). I had the same error and after the uninstall it started working. See this article:

       http://blogs.technet.com/b/exchange/archive/2012/12/14/windows-management-framework-3-0-on-exchange-2007-and-exchange-2010.aspx

       Hope this helps,

       David Garcia

    3. 

       Daniel Wielosz 28 May 2014 Reply

       If you have Exchange 2010 on Windows Server 2012, you need to add -version 2.0 parameter:

       Below you can find definition of task sheduler action:

       powershell.exe -Version 2.0 -command “. ‘c:Program FilesMicrosoftExchange ServerV14binRemoteExchange.ps1’; Connect-ExchangeServer -auto;. ‘c:Program FilesMicrosoftExchange ServerV14ScriptsRedistributeActiveDatabases.ps1’ -DagName DAG -BalanceDbsByActivationPreference -confirm:`$true”

29. 

    M G 24 Nov 2012 Reply

    Hi,
    Thanks Paul
    But how can i make it run automatically ?
    i mean it asks to verify moving databases but i like this script every night run as a scheduled task and fully automatic (i do not want to enter “y” press enter and …)
    i like it to be run without asking for verification

    1. 

       Paul Cunningham 25 Nov 2012 Reply

       Add…

       -confirm:$false

       …to the end of the command.

       1. 

          Ahmed Gamal 22 Jul 2019 Reply

          Run automatically by scheduler task on Action :

          Program/script:
          Start a program: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe

          Add arguments:
          -version 4.0 -NonInteractive -WindowStyle Hidden -command “. ‘C:\Program Files\Microsoft\Exchange Server\V15\bin\RemoteExchange.ps1′; Connect-ExchangeServer -auto; .’C:\Program Files\Microsoft\Exchange Server\V15\Scripts\RedistributeActiveDatabases.ps1’ -DagName DAG-SAPTCO -BalanceDbsByActivationPreference -confirm:$false”

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