Recently, Microsoft announced new rights to build a holistic, high availability (HA) and disaster recovery (DR) plan for SQL Server customers licensing with Software Assurance (SA).
All new benefits can enable significant licensing cost savings for your SQL Server on-premises and on Azure VMs.
What is new?
Enhancements to AlwaysOn Availability Groups
SQL Server 2019 increases from three to five, the maximum number of synchronous replicas supported by AlwaysOn Availability groups.
Additionally, a new secondary-to-primary replica connection redirection feature enables client applications to be connected to the primary replica regardless of the target server specified in the connection string.
Accelerated Database Recovery
This new feature is available in both SQL Server 2019 on-premise and Azure SQL Databases (Standard and Enterprise editions).
The Accelerated Database Recovery (ADR) enables faster database recovery allowing the transaction to log to only be processed from the last checkpoint.
Using a new Persisted Version Store (PVS), ADR accelerates transaction rollback, and long-running transactions do not impact the total recovery time.
Software Assurance Licensing (SA)
The SA customer will be able to add one passive SQL Server instance as a failover server and the other two for disaster recovery purposes (a total of three passive instances).
Applying to all supported versions of SQL Server and both Enterprise and Standard editions, all these instances may run on a separate server.
Figure 1- Software Assurance (SA) Benefits for SQL Server.
Importantly, the passive instances (free) cannot run active SQL Server workloads or data to clients.
Thus, It may only be used to synchronize with the primary server and perform the following maintenance operations:
- Log and Full Back-ups
- Database consistency checks
- Monitoring resource usage data
In the topology below, the primary has two secondary replicas:
- A sync replica for HA supporting automatic failovers
- A asynchronous replica for DR.
As you can see below, if the active replica uses 12 cores, the number of SQL Server core licenses required would be only 12 cores as opposed to 24 cores in the past.
Microsoft is looking to promote its cloud-hosted offering and gain a competitive with the addition of free Disaster Recovery instance hosted in Azure.
Now, SA offers passive replica benefits also running on an Azure Virtual Machine.
The customer will be able to implement hybrid disaster recovery plans with SQL Server.
In the setup below, organizations will need licensing only 12 core too.
A full breakdown of the enhanced benefits are available on the Product Terms available on Microsoft’s website.