Updated June 29, 2023
Introduction to SQL Cluster
Clusters in standard query language (SQL) databases are collections of multiple physical servers grouped using a LAN connection to create a single database with high availability, less hardware failures, and reduced downtime. A SQL Cluster has single shared disk storage where each physical server can store its database files by using their identical access to it. Each physical server must host an instance of the SQL server. In this article, we will be learning about SQL clusters, their advantages and disadvantages, and methods to create SQL clusters.
Advantages
Here are the advantages as follows:
- One of the most important advantages of SQL clusters is that they act as shields to hardware failures. In cases where we have a single database server, the failure in that particular server node leads to a complete halt in the system. But when we have database clusters, this failure can automatically be overcome by passing over the request to the next available node. This is called a cluster failover.
- Upgrades on the SQL server service can be performed simultaneously without turning off the entire service.
- Database clusters help in load balancing as each physical node can attend to different batches of service requests.
- Due to hardware failures, downtime is effectively reduced when database clusters are used instead of standalone sql servers.
Disadvantage
Some of the disadvantages are given below:
- While a very evident disadvantage of database clusters is their inability to recover from database corruption, it is difficult to locate the source of corruption. Also, database clusters have high complexity involved in their design and creation.
- Database clusters are more expensive than standalone SQL servers, and their maintenance and administration are more complex and tedious than the former.
Having known the advantages and disadvantages of SQL database clusters, let’s go ahead and try to learn how to install a SQL Server clustered instance. Before proceeding to the step-by-step guide, I will highly encourage you to go through the list of prerequisites for the installation process:
- Windows PowerShell
- NET Framework 3.5 SP1
- Microsoft Update package (required for SQL Server 2019 and above only. Older versions have Microsoft Update pre-installed in them)
- SQL Server Setup support files
- Do not use unsupported symbols in the cluster name. Some of the unsupported symbols are comparison operators such as (<,>), double and single quotes(“,’), and (&).
- Configuration of all cluster nodes must be the same
- It would help if you did not encrypt or compress the SQL Server installation disk.
- Check Port, Network, and Firewall Considerations. SQL Server’s network name and IP address should not be used for other purposes.
- After installing the operating system and SQL Server instance on each cluster node, do not forget to configure Microsoft Distributed Transaction Coordinator(MDTC).
How to Install a SQL Server Cluster?
Once we have completed all the prerequisites, we are all set to install a SQL server cluster. Here are the steps to it.
- Step 1: To install and configure a SQL server cluster, we must use SQL Server Setup. Download the SQL Server setup from microsoft.com. Next, right-click on setup.exe and run the file as “Run as administrator”. A dialog box will appear in front of you. This is the SQL Server Installation Center. Click on the Installation tab and select “New SQL Server failover cluster installation”.
- Step 2: Enter the product key in the SQL server installation window and click on next.
- Step 3: After clicking on Next, a new window will appear in front of you. Click on the check box to accept the terms and conditions, and finally, click Next.
- Step 4: On clicking Next, SQL Server will ensure that all the rules and prerequisites have been satisfied. If we do not satisfy all the rules, we must start again, ensuring that we have satisfied all the environmental conditions. If yes, you can enable the Next button and proceed by clicking on it. Also, ensure you run a 64-bit SQL Server on 64-bit hardware on a 64-bit Windows operating system.
- Step 5: On the next dialog box, check if you want to receive updates from Microsoft and SQL Server and click Next.
- Step 6: A failover cluster rule will appear before you after clicking Next. A list of both successful and warning rules will be there. Click on Next to go ahead with the installation process.
- Step 7: Once you click Next, a new dialog box with two options will appear: configure SQL Server feature installation and SQL Server PowerPivot for SharePoint. Choose one as per requirement and click on next.
- Step 8: The following dialog box for feature selection will appear. Select the required instance, share features based on requirements, and click Next.
- Step 9: In the following dialog box called instance Configuration window, enter SQL Server Network Name and click on Next.
- Step 10: On the following dialog box called Cluster resource group, select the name of the cluster group and proceed.
- Step 11: Select the disks you want on the cluster disk selection window. Select only shared disks that are part of the current cluster.
- Step 12: On the cluster network selection, enter a unique and unused IP address for the cluster and click on next.
- Step 13: Next, enter the SQL Server service accounts and their respective passwords for Server configuration and click on next.
- Step 14: Next, proceed to the Data directory configuration. Enter the required details while ensuring that the path specified for the TempDB data and log files exists on all the cluster nodes. If this is not the case, SQL Server will fail to come online. Click on Next.
- Step 15: An alert will come before you; click Yes to complete the installation process.
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