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SQL Server 2012 Multi-Site clustering with 2 nodes for HA and DR

    Question

  • Usually we setup 2 Node Prod cluster for Local HA and 1 or 2 Nodes in other data centre for DR

    Given that we have an option to setup multi-site / multi-subnet clustering from SQL 2008 R2/2012. I am planning to use just 2 nodes, 1 in prod data centre and 1 in DR data centre with 2 or 3 instances. This will act as both HA and DR solution.

    I would like to know if this solution is good, and any disadvantages, any best practices, etc.? By implementing this I can save some cost on physical servers.

    Following will be configured:

    * Will be using different subnets, quorum on different server with "Node and File Share Majority"
    * All virtual IPs will be registered for virtual name, and Subnetdelay, Subnet threshold will be modified accordingly
    * All nodes on same domain
    * Use SAN Disk with replication to DR site

    Tuesday, December 31, 2013 3:39 AM

All replies

  • SQL 2008 R2 doesn't support multi-subnet clustering. You would still need 3rd party component like VLAN and Disk Replication. SQL 2012 is the first version to support multi-subnet clustering without using VLAN. you would still need disk replication hardware/software.

    Taken from my book

    {
    Since nodes are often located in two different data centers at geographically dispersed locations, there is no shared storage between the nodes in a multi-site cluster. Clustering across two different data centers provides a higher level of availability and protection at the storage level as we have more than a single copy of the data.

    For SAN replication technology implemented in such clusters, the main activity is to keep data replicated between the sites. Typically, if we have nodes on two different sites, we would have two different network infrastructures and the nodes would be in different subnets. In such cases, if we are on a SQL Server version before 2012, we need to use third party VLAN (Virtual LAN) technology so that one IP address travels between two sites. This is called wide-IP. Companies hesitate with this solution because of the need to buy a third party solution to deploy the VLAN. Using VLAN technology means the same IP address would failover to the remote site in case of a local site disaster. Network administration might consider this as an overhead to maintenance and an extra piece of the networking component that needs to be secure.

    With SQL Server 2012 we do not need to use stretch VLAN technology but SAN replication is still needed for multi-site clustering. The OS version for this can be from Windows Server 2008 R2 and above. In this deployment, we can have a SQL virtual network name having an “OR” dependency on two different IP addresses. One address would be representing each subnet. With the “OR” dependency, if IP1 or IP2 is online we just use the network name. This is one of the Enterprise Editions only features.

    }

    Other option which you can think of, without using 3rd party solutions would be AlwaysOn Availability Group. I have written details about it in my book.


    Balmukund Lakhani | Please mark solved if I've answered your question, vote for it as helpful to help other users find a solution quicker
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    Tuesday, December 31, 2013 5:21 AM
    Moderator
  • Thanks. Will take care of all the pre-requisites.

    I would like to know if anybody using this similar setup (2 Node cluster, 1 in Prod DC and 1 in DR DC).

    Will there be any challenges/issues during failover to another node?

    Any known issues in using combined HA and DR setup with 2 nodes?

    Thursday, January 02, 2014 1:14 AM