SQL 2012 AlwaysON

Posted on 2012-09-10
Last Modified: 2012-12-11
Hello Gurus

I was checking the per-requisites for AlwaysON feature of SQL2012 and found out that we need to have a cluster.
Does this mean that we must have a shared storage ? (SAN)

My idea was to link 2 physical machines with the AlwaysON for HA and redundancy...
will it work if each PC has Win2008 R2 Ent. +SQL 2012 Ent ? (each server has its separate disks).

Question by:ammounpierre
    LVL 28

    Expert Comment

    by:Ryan McCauley
    AlwaysOn requires a cluster, but only to manage the single shared client access point. In this configuration, SQL Server is installed to each server as a stand-alone instance, and the Windows cluster manager is used to create a single network name that clients use to connect, and then the AlwaysOn Availability Group (AG) determines which server the client should talk to.

    You'll need some type of shared storage for your Quorum drive, but it only needs to be about 1GB or so. If you don't have shared storage (like a SAN) handy, you can do iSCSI.

    For those servers, they should be fine for what you're looking to do. Each server will store its copy of the SQL databases on direct-attached, not shared, storage so you're good to go there.

    Author Comment

    and what about the shared storage for the quorum drive ?
    where should it be ?
    on a separate machine?
    any step by step guide how to install this ?
    LVL 28

    Accepted Solution

    If you're going to use iSCSI, you can either target a NAS or a SAN, as long as they support it. Some kind of shared storage like this is a requirement for cluster (and AlwaysOn, since it relies on the cluster service), so I'd look into adding one to your network if you don't currently have one. This is a separate network storage device that other network computers can connect to - if you have a NAS on your network already, it may support iSCSI (if not, you can check out some options at, as an example).

    Here's a technet walk-through for configuring a Windows cluster that's a good place to start:

    Additionally, here's my favorite SQL Server cluster installation walk-through:

    If you have any specific questions, please ask them, but that shoudl cover you for general steps in getting things set up. If you're looking for more understanding of the technology and concepts involved, I'd encourage you to do some reading or refer to a local expert who can help in your situation - while we can provide some insight, it might be helpful to have somebody who can see your currently layout and make recommendations tailored to your environment rather than just general advice.
    LVL 1

    Expert Comment

    AlwaysOn Availability groups do NOT required shared storage.  Just an FYI.
    LVL 28

    Expert Comment

    by:Ryan McCauley
    Touche - I was under the impression at the time that clustering required shared storage, but Windows Server 2008/R2/2012 can do clustering with the quorum as a shared network location instead, so it eliminates the need for shared storage.

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