Clustering is not the solution all the time – Original Posted Feb 8, 2005

Everyone repeat after me, "I will not waste money trying to cluster every freaking service offered by Microsoft servers."

I just feel the need to scream this out loud today. That there are often simpler and easier ways to provide redundancy for some services than using Microsoft server clusters. A couple of quick examples (please write these down) include:

  • Domain Controllers (and Global Catalog servers, too) – It is simple. Install more than one. If one goes down, you still have more. Yes, users can log into a different DC. Yes, users can even log into a different DC in a different physical location. FSMO roles can be seized if the holder of the roles falls out of the server rack and catches on fire.
  • DHCP – THere are lots of great articles on how to split DHCP scopes among more than one server so if one server fails, clients can still get IP addresses.
  • WINS – Think: Primary and Secondary. If the secondary fails, nobody will care or notice (unless it is engulfed in flames). If the primary fails, systems will start using the secondary.
  • DNS – uummmm, use Active Directory integrated DNS. It doesn’t get much more HA than that.
  • Yes, the list goes on and on, but here are some common ones that I see that just make my blood boil

You don’t need multiple nodes and a SAN to provide redundancy all the time. Remember, your company has other needs than have 8 way SMP WINS clusters with 4 TB of shared storage. Please, save a little money and please use some common sense.

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2 Responses to Clustering is not the solution all the time – Original Posted Feb 8, 2005

  1. Temati says:

    Hello Russ,

    I hust reading your post and have a question about the following statment:
    “DNS – uummmm, use Active Directory integrated DNS. It doesn’t get much more HA than that.”
    Recently I had a network fail so many of our branch offices had no connection to the primary DNS in the central site. Than I noticed that many users have compliened about long waiting time for some internet services (internet browsing, fileserver access etc.). I think that this Problem has something to do with the timeout after asking the primary DNS (with the lost connection to the network). So now my idea is to use a fail tolerance feature for DNS, something like NLB or Hardware NLB (Netscaler?)
    – load balance of clinet requests (more than 10000 Clients)
    – no timeout because of NLB

    do you think that is a good idea?

    • If DNS is installed on each of the appropriate servers, AD’s replication process will keep all DNS servers updated. With DHCP configured to deploy the DNS settings, you shouldn’t have any issues with clients needing any reconfiguration.

      Windows Network Load Balancing (NLB) is not a good solution as all nodes of an NLB cluster have to be in the same network segment. Using a hardware load balancer (HLB) just doesn’t make sense as there is a significant increase in cost and complexity.

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