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Two Member DAG - Reboot Witness Server - Effects? RRS feed

  • Question

  • Hi,

    We have a 2 node DAG setup with a CAS Array running on 2 Client Access/Hub Transport servers.

    The Witness disk for the the 2 node DAG resides on the primary HTCA server.

    My question is, what would happen if I reboot the primary HTCA server when installing updates for example?

    Do I get a split brain scenario as both nodes lose site of the witness and they both attempt to become responsible for the mailbox DB in the DAG they are members of?

    Thanks

    Paul

    Monday, December 13, 2010 3:07 PM

Answers

  • Its not going to make any difference to your DAG.
    As FSW will come into picture when theer is failover scenario, as long as DAG is in Active Passive Mode it will remain safe.
    Gulab | Skype: gulab.mallah
    • Marked as answer by pjr2010 Monday, December 13, 2010 3:40 PM
    Monday, December 13, 2010 3:27 PM
  • The key thing is whether something happens to the rest of the DAG while the reboot is taking place. As long as you don't touch the other two servers, then nothing should happen. The FSW only comes in play when one of the servers goes down. A simple reboot shouldn't be a problem.

    Simon.


    Simon Butler, Exchange MVP
    Blog | Exchange Resources
    • Marked as answer by pjr2010 Monday, December 13, 2010 3:41 PM
    Monday, December 13, 2010 3:38 PM

All replies

  • Its not going to make any difference to your DAG.
    As FSW will come into picture when theer is failover scenario, as long as DAG is in Active Passive Mode it will remain safe.
    Gulab | Skype: gulab.mallah
    • Marked as answer by pjr2010 Monday, December 13, 2010 3:40 PM
    Monday, December 13, 2010 3:27 PM
  • Its not going to make any difference to your DAG.
    As FSW will come into picture when theer is failover scenario, as long as DAG is in Active Passive Mode it will remain safe.
    Gulab | Skype: gulab.mallah


    So as long as we dont experience an issue with the 2 mailbox servers whilst the witness server is down for maintenance, we will be OK?

    Thanks

    Paul

    Monday, December 13, 2010 3:29 PM
  • Yes it will be :)
    Gulab | Skype: gulab.mallah
    Monday, December 13, 2010 3:37 PM
  • The key thing is whether something happens to the rest of the DAG while the reboot is taking place. As long as you don't touch the other two servers, then nothing should happen. The FSW only comes in play when one of the servers goes down. A simple reboot shouldn't be a problem.

    Simon.


    Simon Butler, Exchange MVP
    Blog | Exchange Resources
    • Marked as answer by pjr2010 Monday, December 13, 2010 3:41 PM
    Monday, December 13, 2010 3:38 PM
  • While the cluster itself should remain up, it's important to note that if you reboot the FSW, the Active Manager may attempt to move the quorum owner to the other node. That is normal and expected.

    Monday, December 13, 2010 3:59 PM
    Moderator
  • While the cluster itself should remain up, it's important to note that if you reboot the FSW, the Active Manager may attempt to move the quorum owner to the other node. That is normal and expected.

    I take it you are referring to this - http://technet.microsoft.com/en-us/library/dd776123.aspx

    "If the server that owns the cluster quorum resource fails, the PAM role automatically moves to a surviving server that takes ownership of the cluster quorum resource. In addition, if you need to take the server that hosts the cluster quorum resource offline for maintenance or an upgrade, you must first move the PAM to another server in the DAG. The PAM controls all movement of the active designations between a database's copies (only one copy can be active at any specified time, and that copy may be mounted or dismounted). The PAM also performs the functions of the SAM role on the local system (detecting local database and local Information Store failures)."

    In my scenario the server that WAS the cluster quorum would be rebooted (the primary HT/CA server), not the server that OWNS the cluster Quorum resource (assuming I'm correct in thinking that this is the mailbox server that currently hosts the live copy of the Mailbox DB in the DAG?)?

    If this is the case then as the previous posters have stated - nothing should happen

    Paul

     

    Monday, December 13, 2010 4:13 PM
  • No, what I am referring to is the rebooting of the FSW specfically. If you reboot the FSW, the quorum owner may be moved to another server even though you arent rebooting the mailbox node that owns the quorum.

    Tim describes it here:

    http://blogs.technet.com/b/timmcmic/archive/2010/02/15/kb978790-update-to-windows-2008-to-change-the-failure-behavior-of-the-file-share-witness-quorum-resource.aspx

     

     

    Monday, December 13, 2010 6:02 PM
    Moderator