This article gives an overview of Windows Failover Cluster Quorum modes that is necessary for SQL Server Always on Availability Groups.Read more »
This article gives an overview of the Max Worker Threads for the SQL Server Always On Availability Group databases.Read more »
In this article, we will review how to set up auto-failover groups in Azure SQL Server and how failover group is different from active geo-replication in Azure. Auto-failover group is an Azure SQL database feature that replicates one or a group of databases to the secondary Azure SQL server in the cross-region. We cannot have a secondary server in the same region. This feature is used to failover all the databases in the failover group in case of disaster and the failover is automatic.Read more »
In this article, we will review how to set up Geo-Replication on Azure SQL databases. Geo-Replication is an Azure SQL database feature that allows you to create a readable secondary database in the same region or cross-region. We can failover to the secondary database in case of an outage for a long time on the primary database server. We can also use this feature to migrate a database from one server to another server in the same or cross region with minimal downtime. Geo-replication uses the Always-on feature to replicate committed transactions to the secondary database asynchronously.Read more »
SQL Server Always On Availability Groups provides HADR solutions for the SQL databases. Here HA refers to high availability and DR refers to disaster recovery. The priority of this feature is to keep the database highly available and then provide Disaster recovery. Due to this reason, if the secondary replica goes down in a synchronous data commit mode, SQL Server changes commit mode to Asynchronous so that users can continue run the transactions and a secondary replica can be in sync later once it bought up. SQL Listener also points to the primary replica and continues redirects connection to the primary replica.Read more »
In this article, we will review how to setup SQL replication with publisher database in Always On availability groups so that replication continuous to sync even after failover to the secondary server in the availability group.Read more »
SQL Server Always On Availability Groups feature provides high availability (HA) and disaster recovery solutions. We can add multiple databases in a single Always on Availability Group on SQL Server Enterprise edition. Before we add a database in the AG group, we need to use the following checklist.Read more »
In my previous article, Data synchronization in SQL Server Always On Availability Groups, we explored the internal data synchronization for both Asynchronous and Synchronous data commit mode. In the following image, on the secondary replica, we can see two important processes.Read more »
In SQL Server Always On Availability Groups, we can add a database into an existing availability group using different methods. We get the following option in the Initial Data Synchronization wizard in SSMS.Read more »
In this article, we will explore configuring Read Scale Availability Group that does not require a failover clustering configuration. It helps to scale read-only connections to the secondary replica in a cluster less configuration.Read more »
Introduction to SQL Server Statistics
SQL Server Statistics are an essential part of query performance in SQL Server. They help the query optimizer to prepare a query plan using the distribution of values in participating rows. If we do not have updated statistics, it might lead to resource intensive query execution plan. For example, for a large table having a billion records, SQL may choose to have an index scan instead of an index seek.Read more »
This article on SQL Server Always On Listeners includes an overview and various connection configurations for specifying MultiSubnetFailover including SSMS, ODBC, ADO.NET, as well as MultiSubnetFailover limitations and how to connect to all IP addresses via RegisterAllProvidersIP.Read more »
In a high OLTP environment, we may observe strain on CPU and IO due to frequent backups. It might include further complexity due to backup compressions. SQL Server Always On Availability groups provides the capability to perform database backups from the secondary replicas. This article explores Log backups in SQL Server Always On Availability Group.
In my previous article Data Synchronization in SQL Server Always On Availability Group, we described a scenario where if a secondary replica goes down in synchronous data commit mode, SQL Server Always on Availability group changes to asynchronous data commit mode. It ensures that users can get their transaction commit irrespective of waiting for a secondary replica to come online.Read more »
This article describes the data synchronization process on SQL Server Always On Availability Groups in both Synchronous, and Asynchronous data commit mode.Read more »
In the previous article of this series on the SQL Server transaction log, we discuss the SQL Server database recovery models, Full, Simple and Bulk-Logged, and the how the recovery model option of the database affects the way the SQL Server Engine works with the transaction logs. In this article, we will discuss the different types of high availability and disaster recovery solutions and the role of the SQL Server transaction log in these technologies.
In this article, we are going to see how to create a multi subnet cluster spanning across multiple subnets for lab purposes. Creating such an environment should help creating Availability groups simulating a far replica residing in a different Data Center (Subnet) acting as a disaster recovery site in your lab for learning/experimenting real world scenarios.Read more »
In the other article in this series: Deploy SQL Server for failover clustering with Cluster Shared Volumes – part 1 we have seen what a cluster shared volume is and what are the advantages and other considerations to keep in mind when deploying CSVs for SQL Server workloads. In this article, I will walk though actual installation of a failover cluster Instance leveraging CSVs.Read more »
Microsoft SQL Server provides us with a wide variety of solutions to architect High availability (HA) and Disaster Recovery (DR) solutions for mission-critical workloads. In this article, let’s just focus on HA, specifically Failover Clustering. Failover clustering is probably the most mature, robust and stable high availability solution which Windows Server Operating system offers. It’s been there around for few decades now and did evolve over time along with SQL Server. In this article Let’s see a hidden feature of windows server failover cluster which helps in making our already highly available SQL Server Failover clustered instances even more highly available. The new feature which we are going to talk about is Cluster Shared Volumes, AKA CSVs. Considering windows server 2019 is around the corner, I say CSVs are not a new concept in clustering, it’s been there for almost a decade now. Microsoft introduced CSVs in windows server 2008R2, but at that time SQL Server was not supported on CSVs. Well, CSVs were originally designed for Hyper-V workloads and later on enhanced for File servers and eventually landed into SQL Server beginning version 2014.Read more »
This article discusses a simple solution of how to monitor SQL service availability across multiple servers and reporting. To build this I’ll use SQL Server with simple PowerShell script and cmdlets which generate JSON data and displays results in HTMLRead more »
Sometimes our Database fails and we need to reestablish the Database services immediately. Is there a SQL Server solution for high availability?
With Database Mirroring, we can have a replica of the database ready to be used if the main database fails. In this article, we will give a step-by-step tutorial about Database Mirroring. There are other solutions for high availability like high AlwaysOn, Clusters and Log Shipping, but in this chapter, we will start with Mirroring.Read more »
When I configured my first Always-On Availability Group, I setup a Windows Cluster and started with SQL Server Management Studio’s New Availability Group Wizard, scripting out the steps along the way. This entire process took only a matter of minutes. The minimum required steps for configuring the cluster and getting a database into an Availability Group (AG) are very few. This process, however, is deceptively simple. What some don’t realize is that the majority of work required for setting up an AG needs to occur in the planning phase, before a server is even requisitioned. Let us examine the questions that you should ask before implementing an AG.Read more »