Building clusters with Windows Server 2008
One of the biggest gains is the removal of the hardware compatibility list. This was getting hard for Microsoft to maintain and meant that customers with perfectly usable hardware were being told that they couldn’t set up a cluster.
Now there is a feature called Validate, which improves on the old ClusPrep tool. You point to the servers or nodes that you want to use in the cluster and it goes off and tests those servers. If the tests pass, then you can build a cluster using those servers.
To build a cluster using Windows Server 2008:
1. Ensure that you have at least one spare member server that you will use in the cluster.
2. Run Validate on selected servers; this finds servers and checks that they are in the same domain and then allows you to run a series of tests to ensure that they can be used in a cluster. These tests cover everything from the BIOS to the memory, the operating system on the servers to the network and storage connectivity and lots in between. The result is a report that shows every test and the success or failure. This allows you to take corrective action to get servers ready for clustering.
3. Run the Clustering Wizard. As with Validate, tell it the names of the servers you want included in the wizard.
4. Name the cluster.
5. Ensure that the servers all have fixed IP addresses – DHCP can cause problems although the wizard does allow you to specify IP addresses during the configuration.
6. Windows Server will now go to the member servers you have selected as nodes in this cluster and create the cluster.
The first time you create a cluster, there will be a lot of replication traffic. After that, the traffic will be limited to keeping the servers synchronised. As with the domain controller, you can create a cluster on the client site and then add a third machine that will be kept offsite. It is recommended that during the initial phase, the machine is on the LAN to make the best possible use of network traffic. When you then take that machine away, you will need to configure the VPN connections and ensure that the network ID of the remote server is properly maintained along with its credentials.
A cluster on its own does not make the system highly available. There are extra steps to take.
• Run the High Availability wizard from the Cluster Management MMC Snap-In
• Select the service to make highly available – this must be a valid role already installed on the node
• The High Availability wizard will create the service including any network addresses that the service needs
• Once created, any operation you carry out will be assigned
to the cluster, not the individual nodes. This ensures that the loss of a single node will allow the cluster to continue working
Load balancing is in all versions of Windows Server 2008; failover clustering is only in Enterprise Edition. Also, because of the way that Windows Clustering works, you cannot cluster physical and virtual servers together without third-party solutions like PlateSpin Forge.