How can I create a cluster out of two independent SQL Server boxes?

Question

If I have two SQL Server servers running separately, and want to create a clustered environment with them. Do I need to build the Windows cluster first, and then re-install SQL Server , or can I cluster the database engine post-installation?

Answer

Although it is a pain, here is what I suggest:

• The very first step is to backup your databases (system and user) and test your backups to be sure you can restore them.
  
• Verify that the hardware you have is on the Microsoft Hardware Compatibility List.
  
• Attach the shared disk array to the two servers, and test the setup to see that everything works correctly.
  
• Most likely, you don't have a version of the Windows OS that supports clustering , which is necessary for clustering. Because of this, you must rebuild the servers from scratch. By this, I mean to wipe out the previous operating system and then install a version of the Windows OS that supports clustering. You can install the new operating system before or after you install your shared disk array.
  
• Once you have Windows properly installed, then install and test the Windows Clustering Service.
  
• Now you are ready to install SQL Server clustering, and then test it.
  
• Finally, restore your database backups.

If, by chance, you already have a version of the Windows OS that supports clustering installed on these two servers, and if you already a version of SQL Server installed that supports clustering, you still have a lot of work ahead of you, but a little less. Here's what I recommend in this case:

• Backup your databases and test your backups to be sure you can restore them.
  
• Verify that the hardware you have is on the Microsoft Hardware Compatibility List.
  
• Attach the shared disk array to the two servers, and test the setup to see that everything works correctly.
  
• Uninstall SQL Server from both nodes. Leave the databases files intact so that you can reattach them later, if you like.
  
• Install the Windows Clustering Service.
  
• Reinstall SQL Server using the clustering option in Setup.
  
• Finally, restore your database backups, or if all the MDBs and LDFs are still intact, you can reattach them instead of restoring your backups.