subject: How To Set Up A Microsoft Sql Web Server Cluster [print this page] Types of clusters Types of clusters
A cluster is basically referred to as grouping of similar things to reduce the load or work of a single one. When it comes to servers there are 2 types of clusters :
1) Load Balancing Web Server ;
Load balancing Web Server is setup so that the traffic load is distributed among a number of servers instead of one single server. It involves a number of servers which are setup in such a way that the traffic is equally distributed among all of them. Due to this kind of a setup, the network load is not concentrated on one single server and this helps in improving the reliability with the tremendous improvement in performance. This kind of setup is also available for 2 or more nodes in the cluster.
2) Failover cluster Server :
Failover cluster also involves a number of servers but this is not the same as Load Balancing servers. Failover, as the term suggests, is setup to provide high availability even after there is an hardware or software failure. Once there is a software or an hardware failure, an action is taken by the cluster immediately so that the resources of the server are moved to another server. Cluster is informed once the hardware of software failure has taken place as the cluster keeps on monitoring the resources.
Real time failover for hardware and software failures including the current status of the applications can be acheived by fault-tolerant failover cluster. But this requires a better software application and more hardware and this is due to the fact that the condition of the current applications must be known. The applications which are currently in use are lost while the failover process is going on by the hardware and the software components and these should be recovered.
Microsofts Cluster Service (also known as MSCS) is exactly opposite to the true fault-tolerant cluster and is built in as a high-availability cluster. This is better as the cluster will not require specialized fault-tolerant solution and can work with more applications with less hardware also. This will definitely reduce the price. The cluster will not be in a good position after the failover but will be able to recover from a hardware or software failure. Two servers (nodes) are supported by the MSCS high-availability solution.
Basic hardware and software components
A common set of hardware is involved which are actually two servers nodes in a cluster. Both the servers in the cluster are connected to the network and both of them have there own operating system. The harddisks are external but they are connected to the servers through a network. A drive controller connects the shared disks to the servers. A Storage Area Network (SAN) is commonly used for this purpose.
Only one of the nodes in the cluster is active at a time. They are not active together and hence this solution is also called as an active/passive solution. The resources of the cluster is used up by the active server (node) and the active server writes all the data on the Shared disks. If one node fails the other one comes into play. To make sure that all the nodes are working properly, a signal known as a heartbeat is sent accross the private network to which all the servers are connected. If the active server fails, the passive server gets a signal about it through the heartbeats and once it receives the signal, it starts working as an active server and starts using all the resources of the cluster.
How to Install SQL Server in a cluster ?
Operational cluster is required to install SQL server in the cluster. Follow the steps given below to install Operational cluster.
1) First, install a Windows Server edition which supports MSCS on each server.
2) Now, make sure that each server in the cluster is connected to a Public network which is required to receive requests.
3) Make a different network and all the servers shouldnt be connected to this network as this network should only be established between two servers within the cluster. This network will only be used for the heartbeats to send signals.
4) You will have to create a user account for the service account so that the cluster operates under this account in the domain. Make sure that you add this account to each Administrators group of each server.
5) Now you will have to connect the Shared harddisks to the server and you will have to power off the servers for this purpose. Once you connect the Shared harddisks to the servers make sure that the resources are being used by the server. Turn on node number one of the cluster.
6) Install Microsoft Cluster service and then configure it through control panel. Follow the steps given below to do this.
a. Go to Control Panel.
b. Then, Add/Remove Programs
c. Finally, Windows Components
7) You will have to give a name to your cluster and also assign an IP address with the Shared disk resources.
Now turn on the second node in the cluster and move to the First one (Original one) once the second one is online. Once you get back to the original one, to add another node use the Cluster Administrator.
Note : You will be able to install the second node quite easily in comparison to the first one as it will be based on the configuration of the second one.
Once you have installed the cluster sucessfully and everything works fine, follow the steps given below to install SQL server into the cluster :
1. To begin the installation process, you will have to insert the SQL Server Enterprise edition CD. If the installation does not start auto-matically, launch the setup through setup.exe.
2. Select Virtual Server on the computer name screen and enter a name by which you would like the Cluster be referred.
Note : This name is a Virtual name and is just like the hostname of a server.
3. Now make a service account to run the SQL web server and make sure that you provide Administration rights on each node on the cluster.
4. You will have to assign an IP address, Shared Resources and a service account to the SQL server while the installation.
Once you have done all the above steps correctly, a copy of SQL Server server will be installed on each node by the setup program within the cluster and the setting of the cluster will be installed automatically. Now you will be able to control the SQL server services by the cluster administrator.
