SQL Server Performance

Clustering on live servers

Discussion in 'SQL Server 2008 Clustering' started by cnikirk, Mar 17, 2010.

  1. cnikirk Member

    Hi,
    I need to implement an active/active cluster on two live servers. I am very reluctant to do this on live servers. How large of a risk is it to implement a cluster on live servers. I'm not sure what can go wrong and how much down time to expect.
    Thanks.
  2. satya Moderator

    What do you mean by 2 live servers?
    From SQL 2008 onwards there is no concept like Active/Active or Active/passive, in your case it means there will be 2 active SQL instance running at same time.
    term Active/Active seems to imply that this would be the case, which is why we typically try to refer to them as Multi-instance clusters now instead of the Active/Active label. Active/Active in the MSCS world basically means that you have 2 independent Sql Server instances running on 2 cluster nodes - these instances are independent of each other in all respects, obviously unless you link them in some manner with custom business logic, replication, etc. Think of them for all intents and purposes as 2 seperate instances running on seperate servers at all times (as that's what they really are)...the only difference being that in case of a physical node failure (or service failure on a node), the instance will be moved to and hosted on a second physical server.
    I'd be curious to know what research you came across that implied load-balancing as a feature with MSCS so we can try and get it corrected, or possibly clarify what position the author was taking.
    To support load-balancing, or scaling out in a Sql Server environment you have a couple of different options, depending on your edition, environment, version of Sql, etc. Take a look at the following articles for a start:
    http://msdn2.microsoft.com/en-us/library/aa479364.aspx
    http://www.microsoft.com/technet/prodtechnol/sql/2005/scddrtng.mspx
  3. cnikirk Member

    What I mean by live servers is they are already in production with databases on them. I can't afford a lot of downtime to turn on clustering services or risk screwing up the SQL Server install. Does that make sense?I'm not interested in load balancing, but high availability.
  4. satya Moderator

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