1. AlwaysOn Availability Groups 101
Using SQL Server 2012

2. About Me Jeff Reinhard 20 years database development experience
@jreiny
Employment Highlights:
Ernst & Young
Internet Security Systems/IBM
AirWatch
WebMD
CheckFree
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AlwaysOn Availability Groups 101

3. Pyramid Analytics Thank You Microsoft for the facility
For sponsoring tonight’s event:
Pyramid Analytics
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AlwaysOn Availability Groups 101

4. Agenda What is AlwaysOn Prerequisites Setting Up Monitoring
AlwaysOn and Your Application
Lessons Learned
Q&A
34 slides, so I need to move fast
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5. Two Types of AlwaysOn ??? AlwaysOn Failover Cluster Instances
leverages Windows Server Failover Clustering (WSFC) functionality to provide local high availability through redundancy at the server-instance level—a failover cluster instance (FCI).
Previously known as SQL Clusters
Works with SQL Server Standard Edition
AlwaysOn Availability Groups (AG)
This presentation discusses further
Requires SQL Server Enterprise Edition
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6. What Is AlwaysOn AG?
AlwaysOn is SQL Servers best available technology for SQL High Availability.
AlwaysOn is a new integrated, flexible, cost-efficient high availability and disaster recovery solution. It can provide data and hardware redundancy within and across data centers, and improves application failover time to increase the availability of your mission-critical applications. AlwaysOn provides flexibility in configuration and enables reuse of existing hardware investments.
The principal goal of a high availability solution is to minimize or mitigate the impact of downtime.
It is recommended for scenarios where high availability is required and the application will benefit from readable copies of the primary databases.
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7. AlwaysOn Architecture Overview
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8. Prerequisites – Before you begin
Prerequisites, Restrictions, and Recommendations for AlwaysOn Availability Groups
AlwaysOn Failover
Do not use the Failover Cluster Manager to manipulate availability groups, for example:
Do not add or remove resources in the clustered service (resource group) for the availability group.
Do not change any availability group properties, such as the possible owners and preferred owners. These properties are set automatically by the availability group.
Do not use the Failover Cluster Manager to move availability groups to different nodes or to fail over availability groups. The Failover Cluster Manager is not aware of the synchronization status of the availability replicas, and doing so can lead to extended downtime. You must use Transact-SQL or SQL Server Management Studio.
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9. Prerequisites – Before you begin (cont.)
AlwaysOn Quorum Resources
Connecting with multi-subnet failover
Availability Group Listeners, Client Connectivity, and Application Failover (SQL Server) -
Creating a listener
Prerequisites and requirements
Only one listener can be created though SQL Server.  If you need an additional listener, it can be created thought WSFC.
Recommendation, use a static IP for multiple subnet configurations.
You must be connected to the instance that hosts that primary replica
If using static IP addresses, the listener will have a static IP  for each subnet that has a replica.
Configure Read-Only Routing for an AG
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10. Prerequisites - Windows Cluster
Go into Server Manager, features, add features
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11. Prerequisites - Windows Cluster (cont.)
Enable Failover Clustering
Make sure cluster services are available on all participating nodes
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12. Prerequisites - Windows Cluster (cont.)
Add the database servers to the cluster
Run validations, tests, etc.
Some warnings are due to no storage available to the cluster, which is correct for AlwaysOn.
Create the cluster
Create Active Directory computer account for cluster name
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13. Prerequisites – SQL Server Configuration
Open SQL Server Configuration Manager
Select SQL Server Services, right click on SQL Server, select properties
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14. AlwaysOn Set Up
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15. AlwaysOn Setup - Overview
Working Primary Node
Available “blank slate” secondary
Create Availability Group
Select Databases
Specify Replicas
Create the AG Listener
Select full data synchronization
Run the wizard
Configure Read Only Routing
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16. AlwaysOn Setup - Working Primary Node
Ensure your application is working properly
Review logins and users and permissions
Using Contained databases is recommended but not required
If not using contained databases, export the logins
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17. AlwaysOn Setup - Available “blank slate” secondary
Secondary Node(s) should match the primary in configuration, version, etc.
Make sure the databases and files on the primary do not exist on the secondary
If not using contained databases, import the logins used by the application.
Don’t import default and windows authentication accounts
It is vital that the login SIDS match between the primary and secondary node(s)
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18. AlwaysOn Setup - Create Availability Group
Using SSMS, from your primary database node, start the New Availability Group Wizard and give it a name
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19. AlwaysOn Setup - Select Databases
Select all of the databases that work together as a set for your application; possibly including Reporting Services database(s).
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20. AlwaysOn Setup - Specify Replicas
The wizard will select your primary node, add your secondary node(s)
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21. AlwaysOn Setup - Specify Replicas (cont.)
For all, select Synchronous, Automatic Failover, Readable Secondary = Yes
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22. AlwaysOn Setup - Create the AG Listener
On the listener tab, enter name and port 1433, then click add for IP
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23. AlwaysOn Setup - Create the AG Listener (cont.)
Enter the IP address for the listener
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24. Select full data synchronization
Create the folder, preferably on a secondary node, then enter into the wizard
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25. Run the wizard
Perform the validation, next, then finish to create the AG
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26. Configure Read Only Routing
I have a script that with the setting of a few variables, will generate the code to perform the configuration. Contact me and provide payment if interested.
What is important after configuration
Endpoint_url uses DNS name and port 5022
Available mode is synchronous
Failover mode is automatic
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27. Configure Read Only Routing (cont.)
What is important after configuration (cont.)
Primary role allow connections is ALL
Secondary role allow connections is READ_ONLY
ReadOnly Routing URL is IP and port 1433
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28. AlwaysOn Monitoring - Dashboard
The first place to start is the dashboard
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29. AlwaysOn Monitoring – Top Section
Look for any errors, warnings, check that failover mode is automatic, AG group state is healthy, check the links on the right for any errors or warnings
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30. AlwaysOn Monitoring - Replicas
Check the health icon, failover mode is automatic, synchronization state is good, and no issues reported
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31. AlwaysOn Monitoring - Databases
Check the primary and secondary, health state, synchronization state, failover readiness, issues
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32. AlwaysOn Monitoring (cont.)
There are many DMV queries that can be used
Microsoft SQL Server 2012 AlwaysOn Monitoring Management Pack
AlwaysOn Availability Groups Troubleshooting and Monitoring Guide
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33. AlwaysOn and Your Application
The connection strings should all go to the listener, not directly to any database server instance
To have your application use the primary mode, no change is required in your connection string
To have your application use a readable secondary, add to the connection string:
;ApplicationIntent=ReadOnly
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34. AlwaysOn Lessons Learned
Request the DNS name and IP for windows cluster and Availability Group Listener early, they can take a while
Research prerequisites, make sure all patches, versions, components are optimal to support AlwaysOn
Schedule and plan out in advance, get key players on board in the beginning
Schedule implementation in two phases:
Configuration of clusters, storage, SQL server stand alone instances
Implementation of AlwaysOn
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35. Bonus Trick ALTER DATABASE [XXXXX] SET HADR RESUME;
Sometimes, when a database is in the state of “not synchronizing”, and all other issues have been resolved, running the below command might get it back to healthy:
ALTER DATABASE [XXXXX]
SET HADR RESUME;
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36. Thank you for your time! Questions? 9/18/2018 |
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AlwaysOn Availability Groups 101