Preparing the SQL Server 2005 Clustering Infrastructure

Before you even begin building a SQL Server 2005 cluster, you must ensure that your network infrastructure is in place. Here's a checklist of everything that is required before you begin installing a SQL Server 2005 cluster. In many cases, these items are the responsibility of others on your IT staff. But it is your responsibility to ensure that all of these are in place before you begin building your SQL Server 2005 cluster.

• Your network must have at least one Active Directory server, and ideally two for redundancy.
• Your network must have at least one DNS server, and ideally two for redundancy.
• Your network must have available switch ports for the public network cards used by the nodes of the cluster. Be sure they are manually set to match the manually set network card settings used in the nodes of the cluster. In addition, all the nodes of a cluster must be on the same subnet.
• You will need to secure IP addresses for all the public network cards.
• You must decide how you will configure the private heartbeat network. Will you use a direct network card to network card connection, or use a hub or switch?
• You will need to secure IP addresses for the private network cards. Generally, use a private network subnet such as 10.0.0.0 – 10.255.255.255, 172.16.0.0 – 172.31.255.255, 192.168.0.0 – 192.168.255.255. Remember, this is a private network only seen by the nodes of the cluster.
• Ensure that you have proper electrical power for the new cluster servers and shared array (assuming they are being newly added to your data center.)
• Ensure that there is battery backup power available for all the nodes in your cluster and your shared array.
• If you don't already have one, create a SQL Server service account to be used by the SQL Server services running on the cluster. This must be a domain account, with the password set to never expire.
• If you don't already have one, create a cluster service account to be used by the Windows Clustering service. This must be a domain account, with the password set to never expire.
• Create three global groups, one for the SQL Server Service, the SQL Server Agent Service, and the SQL Text Service. You will need these when you install SQL Server 2005 on a cluster.
• You will need to determine a name for your virtual cluster (Clustering Services) and secure a virtual IP address for it.
• You will need to determine a name for your virtual SQL Server 2005 cluster and secure a virtual IP address for it.
• If you are using a Smart UPS for any node of the cluster, remove it before installing Cluster Services then re-add it.
• If your server nodes have AMP/ACPI power saving features, turn them off. This includes network cards, drives, etc. Their activation can cause a failover.

I have included this list here so you understand that these are the steps you need to take before actually beginning a cluster install.

Preparing the Hardware

Based on my experience building clusters, the hardware presents the thorniest problems, often taking the most time to research and configure. Part of the reason for this is that there are many hardware options, some of which work, and others that don't.

Unfortunately, there is no complete resource you can use to help you sort through this. Each vendor offers different hardware, and the available hardware is always changing, along with new and updated hardware drivers, making this entire subject a moving target with no easy answers. In spite of all this, here is what you need to know to get started on selecting the proper hardware for your SQL Server 2005 cluster.

Finding Your Way Through the Hardware Jungle

Essentially, here's the hardware you need for a SQL Server cluster. To keep things simple, we will only be referring to a 2-node active/passive cluster, although these same recommendations apply to multi-node clusters. The following are my personal minimum recommendations. If you check out Microsoft's minimum hardware requirements for a SQL Server 2005 cluster, they will be somewhat less. Also, I highly suggest that each node in your cluster be identical. This can save lots of installation and administrative headaches.

Server Nodes

• Dual CPUs, 2 GHz or higher, 2MB L2 Cache (32-bit or 64-bit)
• 1GB or more RAM
• Local mirrored SCSI drive (C:), 9GB or larger
• SCSI DVD player
• SCSI connection for local SCSI drive and DVD player
• SCSI or Fiber connection to shared array or SAN
• Redundant power supplies
• Private network card
• Public network card
• Mouse, keyboard, and monitor (can be shared)

Shared Array

• SCSI-attached RAID 5 or RAID 10 array with appropriate high-speed SCSI connection. With Microsoft Clustering, SCSI is only supported if you have a 2-node cluster. If you want to cluster more than two nodes, you must use a fiber-attached disk array or SAN.

Or

• Fiber-attached RAID 5 or RAID 10 array with appropriate high-speed connection.

Or

• Fiber-attached SAN storage array with appropriate high-speed connection (a fiber switch).

Because hardware varies so much, we won't spend much time on hardware specifics. If you are new to clustering, I would suggest you contact your hardware vendor for specific hardware recommendations. Keep in mind that you will be running SQL Server 2005 on this cluster, so ensure that whatever hardware you select meets the needs of your predicted production load.