What are the always on availability groups in SQL Server?

What are the always on availability groups in SQL Server?

SQL Server 2017 introduces two different architectures for availability groups. Always On availability groups provide high availability, disaster recovery, and read-scale balancing. These availability groups require a cluster manager.

Can a sysadmin collect availability group latency data?

The Availability Group Latency data collection feature is only enabled for sysadmin (only Windows Authenticated) accounts and requires that the current user account be an admin on all the replica instances. This functionality can only be used to collect latency data for one Availability Group at a time.

How to create AlwaysOn latency data collection job?

For the latency Data collection to work, we require SQL Agent to be running on at least one secondary replica and the Primary Replica. Create a SQL Agent Job with the name “AlwaysOn_Latency_Data_Collection”.

Is there a dashboard for AlwaysOn availability groups?

AlwaysOn Availability Groups latency can be a real concern. Microsoft provides a AlwaysON Dashboard to monitor and some administration of Availability Groups in SQL Server Management Studio (SSMS). Ben Snaidero as an excellent posting about the dashboard and T-SQL monitoring of AG.

Do you need failover cluster for always on availability groups?

Deploying Always On availability groups requires a Windows Server Failover Cluster (WSFC). To be enabled for Always On availability groups, an instance of SQL Server must reside on a WSFC node, and the WSFC and node must be online. Furthermore, each availability replica of a given availability group must reside on a different node of the same WSFC.

What is an example of a distributed availability group?

For example, if the AG containing the read/write primary replica is SQL Server 2016, but you want to upgrade/migrate to SQL Server 2017 or later, the other AG participating in the distributed AG can be configured with SQL Server 2017.

Do you need shared storage for always on availability groups?

Always On availability groups does not depend on any form of shared storage. However, if you use a SQL Server failover cluster instance (FCI) to host one or more availability replicas, each of those FCIs will require shared storage as per standard SQL Server failover cluster instance installation.

Do you need a WSFC for always on availability groups?

Always On Availability Groups (AGs) require an underlying Windows Server failover cluster (WSFC). Deploying a WSFC through Windows Server 2012 R2 has always required that the servers participating in a WSFC, also known as nodes, are joined to the same domain.

Can a basic availability group be upgraded to advanced?

Basic availability groups cannot be upgraded to advanced availability groups. The group must be dropped and re-added to a group that contains servers running only SQL Server 2016 Enterprise Edition. Basic availability groups are only supported for Standard Edition servers.

What causes failovers in an always on availability group?

An availability replica provides redundancy only at the database level for the set of databases in one availability group. Failovers are not caused by database issues such as a database becoming suspect due to a loss of a data file or corruption of a transaction log.

Is the AlwaysOn the new active or passive?

It’s official – as I predicted with in my Availability Groups FAQ just over a year ago, the term AlwaysOn has now become the new active/passive and active/active and annoys me just as much if not more. Every time I see it misused I want to proverbially stab myself in the eyes.

What does AlwaysOn stand for in SQL Server?

It is a marketing term that covers two features in SQL Server: availablity groups (AGs) and failover clustering instances (FCIs). So their official names are technically AlwaysOn availability groups and AlwaysOn failover cluster instances (or failover clustering instances).