Do you need two nodes when installing a cluster?

  • Seems like a silly question, right? I have a project that requires SQL Server to be set up on a cluster. Through some mixup one of the servers to be used in the cluster was not ordered and will not be here in time to meet the project deadline.

    Can I actually get through the Windows Server 2003 Cluster and SQL Server 2005 installations having only one node? I'll add the second node when the hardware arrives. Trying to avoid a big cleanup later.

  • To my knowledge, you can install a one-node cluster within Windows, and then add servers to the cluster as they come in.

    However, I believe you will need to re-run the SQL Server installation in order to make it a failover cluster. The reasoning for this is that the SQL binaries will need to be installed on that secondary node, and the services will need to be configured properly.

    I have not personally come across this, but I can propose how I would approach it.

    One way to handle this would be to install one instance at the initial install (make this a named instance, SERVERNAME\INST2), and then install the default instance during the second install.

    The logic there would be to install 1 instance for use now, then migrate into the 2nd instance (which is installed as a failover cluster) after the new server is added to the cluster.

    In order to install the 2nd instance on the cluster, additional LUN's will be needed.

    The final SAN config that I would recommend is this:

    1 LUN for each of the following:

    1. system DB data and logs (master, model, msdb, SQL error log) (25GB, my SAN team only presents LUN's in 25GB)

    2. temp DB data (50GB)

    3. temp DB log (25GB)

    4. user DB data (100GB, varies)

    5. user DB logs (50GB, varies)

    6. backups (sometimes use local disk for backups)

    7. MS DTC (25GB)

    8. Quorum (25GB)

    You'll need to divide up the disk so much as to leave enough to install the second instance and move everything over, or have new LUN's presented by your SAN admin to facilitate the migration to the second instance.

    In my example, you'll need a total of 300GB for the initial instance, then another 250GB to make a parallel installation (the MS DTC and Quorum would remain).

    Then, you migrate all DB's and logins from Inst2 to the default instance. After that is complete, you can uninstal Inst2.

    I would be intrigued if someone posted who has added a node to a cluster successfully before to know how to get around my logic and save time.

    In any event, I hope that makes sense and gives a little guidance.

    Thanks,

    Steve

  • can't we install on one server and add the other node later?

    What if we want to upgrade a standalone to a cluster environment and if we want to use the standalone as another node?

  • That wouldn't be possible. The clustered instance would need to have disk that is only presented to the Windows cluster. The databases, logins, etc would need to them be moved into the clustered instance of SQL Server which will have a new network name, new IP, resulting in changes needed at the application layer.

    You could run a standalone and a clustered instance on the same node, but they wouldn't use the same disks.

    Hope that helps,

    Steve

  • This may be an issue with SQL Server 2005 as the installer activly runs install scripts on the 2nd node when you install on the first node. So after the first install all you need to do is install the client tools on the 2nd node.

    If you can go to SQL Server 2008 or higher, it's definitely possible to install a single node cluster as the install on the first node doesn't do anything on the 2nd node. The second node is then a seperate install, and done via the "add a node to a cluster" option.

    I've got customers who have done this while upgrading. They bought a new server, built a single node cluster and migrated to the new hardware, then dismantled the original hardware and used it to build the second node of the cluster.

    Cheers

    Leo

    Leo
    Nothing in life is ever so complicated that with a little work it can't be made more complicated.

  • Thanks a lot !!!!!

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