Planned outage in small DAG DAC configuration; Exchange 2010 sp3

Posted on 2014-08-08
Last Modified: 2014-08-14
-In the process of designing a 2 site 2 multi-role server DAG
-Exchange 2010 sp3 ru6
-server 2008 r2 enterprise
-There will be 1 primary data centre and one DR datacentre connected via a 100mb WAN link
-There is 1 Witness Server in the primary datacentre
-DAC Mode enabled

There is one scenario that I cannot find any documentation on.  We have plans for WAN outages, and total site failures but not planned site outages.

What I would like to know is how to handle a planned outage of the primary site like building maintenance causing a power outage.  Can site B be activated as the active database a couple of days before the outage gracefully and then gracefully switch back when the maintenance is complete and the primary site comes back online?  I want to avoid treating a planned site outage as a disaster recovery situation.


Question by:tnorman
    LVL 63

    Accepted Solution

    If you know the outage is coming, simply switch the FSW to a server in the second data centre. You can then failover to that site immediately before the outage starts and Exchange will stay operational.
    Once the job is done, fail back and change the FSW.

    You don't want to leave the FSW in the remote data centre, as that would mean a problem with the inter-site link would result in no one being able to use email during the outage. If the server was up, then internal email would work and external would queue.

    LVL 27

    Assisted Solution

    any 2 server DAG is going to have problems as the server witness can only exist at one of the sites. the ideal solution is to have the witness at an independent location that both sites can see, but this isn't practical for many people.

    I agree that moving the witness to the 2nd site well before having the outage may be the simplest way to ensure stability. any other option wouldn't be guaranteed to work automatically.

    if you don't mind doing stuff manually however, you would be fine to shut down the main site and then manually activate the DBs at the 2nd site.

    Author Comment

    When you say move the fsw to the new site is that literally? Or can we activate the alternate fsw in the DR site and get the result we're after?
    LVL 63

    Expert Comment

    by:Simon Butler (Sembee)
    I mean make another machine the FSW. If you have configured an alternate FSW then you can use that instead. The alternate FSW is not activated automatically.


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