All the things you need to know before setting up AlwaysOn Michael Steineke SQL & BI Solution Lead Enterprise Architect Concurrency, Inc.

Terminology and Architecture  AlwaysOn  Marketing name for the high availability features in SQL Server  Includes  Fail over Cluster Instances (FCI)  Availability Groups (AG)  Windows Server Failover Clustering (WSFC)  All of AlwaysOn uses WSFC

High Availability vs. Disaster Recovery  High Availability  Generally same site  Quick Recovery  Disaster Recovery  Separate Site  Slower Recovery

Site to Site Considerations  How far apart are they?  What is the connectivity between sites?  Type of connection  Size of connection  Latency of connection

Networking  Server to server connectivity  Ports to open on Firewalls  TCP Ports 1433 & 1434 or specific SQL ports  AG Endpoint – tcp 5022  IP Addresses  DNS Names & IP Addresses  Servers, Cluster Name, AGs

Windows Clustering  What do I need to know as a DBA?  Management  Windows Failover Cluster Manager  PowerShell  Windows Domain  Joined  Authentication  SQL Server needs to run as a Domain Account  Connectivity  DNS Names and SQL Instances  Availability Group Listener  Ports  Quorum

Why do I care about Quorum?  Quorum Controls if the Cluster in Online  Majority of votes  What can vote?  Shared Disk  Servers – Active, Passive or Witness  File Share – Witness  Manual Voting override is available  In Multi-Site configurations you need to decide where the voting members are located

Windows Server Version & Clustering  Windows Server 2012 R2  Many useful updates to clustering  Dynamic Quorum  Cluster automatically controls Voting  Adjusts the vote weight of each node  Allows for Last Man Standing  Network Resiliency  Key to making sure the Cluster is healthy

Cluster Network Objects  Computers in AD  AD OU  Permissions  Cluster and Listener Objects in AD

OU Delegation  Create an OU and Delegate to the Cluster Account

SQL Server Version Comparison SQL 2012 Enterprise  Multiple Node FCI  Multi-Subnet Clusters  AG’s – 5 Copies of Data  4 Secondaries Total  2 Synchronous  Up to 4 Asynchronous  2 Automatic Failover Targets  Readable Secondaries SQL 2014 Enterprise  Multiple Node FCI  Multi-Subnet Clusters  AG’s – 8 Copies of Data  7 Secondaries  2 Synchronous  Up to 7 Asynchronous  2 Automatic Failover Targets  Readable Secondaries  Azure Replica  Backup to Azure  Site Survivability for Read Intent

FCI or AG?  If you need MSDTC, AGs don’t support MSDTC  AGs require separate Disk for each Instance  AGs can fail from node to node faster than FCI  Synchronous AGs require transactions to commit(log harden) on both servers  AG Secondaries can do workload  Backup & Read-only Answer – It depends on your needs You might want to combine them!

MSDTC  In Windows 2008 and later you either Create a clustered instance of the MSDTC resource for EVERY SQL Server instance /Group that requires its functionality or DO NOT CLUSTER MSDTC at all  View msdtc mappings  msdtc -tmMappingView *

Availability Group Setup  Shared Backup location  Permissions on share  Full on SQL Server Account

Multiples – Instances, AGs  You can have multiple AGs in an instance  Listeners are tied to AG  Multiple Instances  Each AG needs different ports for the endpoints  AG’s on Private Network

Multi-subnet  DNS  Client App connectivity  d-multisubnet-listener-behavior-with-newly-released-sql-client- provider-in-net-4-6-1/ d-multisubnet-listener-behavior-with-newly-released-sql-client- provider-in-net-4-6-1/  JDBC - us/library/gg558121(v=sql.110).aspxhttps://msdn.microsoft.com/en- us/library/gg558121(v=sql.110).aspx  Azure Listener  readintent-routing-with-azure-alwayson-availability-group-listener/ readintent-routing-with-azure-alwayson-availability-group-listener/

Enabling AGs

What you need before the Wizard  Network Names  Cluster name  Listener Name  Firewall Rules/ports open  Listener  AG  IP Addresses  Each Server  Cluster Name  Each Listener  Active Directory  Permissions or Objects staged  Servers in OU  File System  Location of DB Files  Shared Backup Location

Useful Reference Links  SQL AlwaysOn Team Blog   SQL Server Customer Advisory Team   SQL Server 2014 Technet Reference   SQL High Availability on MSDN   Failover Cluster Guide to Quorum   Prestage Computer Objects in AD   MSDTC   AGs on Private Network   SQL 2016 Changes to AGs 

Thanks!   