Announcement

Collapse
No announcement yet.

Exchange DAG Questions

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Exchange DAG Questions

    I have a DAG across two Sites, consisting of a CAS/Mailbox server and FSW in Site A, and a CAS/Mailbox server in Site B. I have a single namespace mynamespace.company.com.

    Recently, the main server has had a few cluster issues and has activated the DBs automatically on the Site B. The result of this is that OWA/ActiveSync/Outlook Anywhere stop working until the DBs are pushed back.

    I have set activation to block automatically activating across sites, but my understanding would be that I would expect Exchange to be able to proxy the various requests across to Site B, as both servers were effectively online.

    If that isn't the case, am I correct in thinking I would need to manually update the A record of the DNS namespace in order for mailboxes in Site B to work with OWA/ActiveSync/Outlook?

    Ideally I'm looking for as near a seamless solution as possible, in the event that the DBs are switched over without lots of manual intervention to get things working again.

    Any feedback appreciated!

  • #2
    Re: Exchange DAG Questions

    The only way you will get seamless is to have a hardware load balancer in place.
    However for most of the clients I work with, they don't want site failover to happen automatically, but to occur in a more controlled manner.

    Web services will only proxy to the other server IF there is no external URL configured on the second server. If there is an external URL then they should redirect to the relevant URL.

    Do you have an RPC CAS Array in place? Does it resolve internally only? If not, then you are going to struggle to get clients to connect to the second server automatically.

    Do you have DAC mode enabled?

    Simon.
    --
    Simon Butler
    Exchange MVP

    Blog: http://blog.sembee.co.uk/
    More Exchange Content: http://exchange.sembee.info/
    Exchange Resources List: http://exbpa.com/
    In the UK? Hire me: http://www.sembee.co.uk/

    Sembee is a registered trademark, used here with permission.

    Comment


    • #3
      Re: Exchange DAG Questions

      Originally posted by Sembee View Post
      The only way you will get seamless is to have a hardware load balancer in place.
      However for most of the clients I work with, they don't want site failover to happen automatically, but to occur in a more controlled manner.

      Web services will only proxy to the other server IF there is no external URL configured on the second server. If there is an external URL then they should redirect to the relevant URL.

      Do you have an RPC CAS Array in place? Does it resolve internally only? If not, then you are going to struggle to get clients to connect to the second server automatically.

      Do you have DAC mode enabled?

      Simon.
      Thanks for your reply.

      My client wont be purchasing a hardware load balancer, and as you say, failover will be in a controlled manner.

      The external URL on the second server is set to match the primary server, so that in the event that we need to failover, it would be a case of updating the A record for the namespace. I chose this design as I felt it required the least effort to get Outlook and ActiveSync clients up and running again, as the namespace wont have changed, and in theory should require no reconfiguration clientside.

      I realise I am a little late in creating a RPC Cas array as the Outlook clients are already autoconfigured. Is there a benefit to creating a single RPC array in each site, or have one stretched across both sites - if that's possible?

      I haven't enabled DAC mode, is this generally recommended?
      Last edited by marcus2704; 2nd September 2014, 14:38.

      Comment


      • #4
        Re: Exchange DAG Questions

        RPC CAS Array are AD site specific, so you cannot stretch one across the sites. You should create one immediately and start the process of updating the client to use. It is quite simple to do - just choose the Repair option in the Outlook account configuration. New Outlook profiles will get it immediately.

        I wouldn't have the same URLs configured on both sides though. DNS records take longer to update than URL changes, due to the caching involved, particularly on the internet. Have two sets of URLs, if you do have a full site failover then change the configuration at that point. With a script it takes less than 30 seconds.

        As for DAC mode, that should be enabled when you are using two separate sites.

        Simon.
        --
        Simon Butler
        Exchange MVP

        Blog: http://blog.sembee.co.uk/
        More Exchange Content: http://exchange.sembee.info/
        Exchange Resources List: http://exbpa.com/
        In the UK? Hire me: http://www.sembee.co.uk/

        Sembee is a registered trademark, used here with permission.

        Comment


        • #5
          Re: Exchange DAG Questions

          Many thanks for your helpful replies.

          Comment

          Working...
          X