1. Designing Database Solutions for SQL Server
Christian Bolton | Technical Director, Coeo
Graeme Malcolm | Microsoft

2. Course Topics Designing Database Solutions for SQL Server
01 | Managing a SQL Server Environment
02 | Designing Database Security
03 | Designing a Backup & Recovery Solution
04 | Designing a High-Availability Solution
05 | Troubleshooting & Maintaining a database

3. Christian Bolton | Technical Director, Coeo Graeme Malcolm | Microsoft
04 | Designing a High-Availability Solution
Christian Bolton | Technical Director, Coeo
Graeme Malcolm | Microsoft

4. Module Overview Log Shipping Windows Server Failover Clustering
AlwaysOn Failover Clustering
AlwaysOn Availability Groups
Advanced deployment scenarios

5. Log Shipping Log shipping is a three-phase process
Backup log on primary server
Copy log to secondary server
Restore log on secondary server
Secondary servers can be readable but be aware of caveats
Manual failover to secondary servers

6. Windows Server Failover Clustering
SQL Server AlwaysOn technologies rely on Windows Server Failover Clustering
A Windows Server Failover Cluster includes
Cluster nodes
Cluster resources
Cluster roles
Failover
Cluster
Instance
Each node maintains a copy of the cluster configuration
During failover and failback, ownership of resources passes from one node to another
Windows Cluster

7. Quorum
Quorum defines the minimum number of votes required for the cluster to remain online
More than 50% must be counted to achieve quorum
Quorum configurations
Node majority
Node and disk majority
Node and file share majority
Disk only

8. AlwaysOn Failover Clustering
SQL Server is a cluster-aware application
Instance-level protection – databases, logins, Scheduled Jobs
Transparent to end-user applications
Requires shared storage
SQL Server installations are Failover Cluster Instances (FCI)

9. Enhancements to AlwaysOn Failover Clustering
Enhancements in SQL Server 2012
Detailed health monitoring
Flexible failover policies
Improved troubleshooting
Support for multi-subnet clustering
Local tempdb
Enhancements in SQL Server 2014
Support for Cluster Shared Volumes

10. Enhancements to AlwaysOn Failover Clustering
The sp_server_diagnostics stored procedure provides health monitoring and flexible failover policies
5 – Failover/restart on any qualified failure conditions
4 – Failover/restart on moderate SQL Server errors
3 – Failover/restart on critical SQL Server errors
2 – Failover/restart on server unresponsive
1 – Failover/restart on server down
0 – No automatic failover

11. AlwaysOn Availability Groups
Listener
Clustered Network Name
Clustered IP Address
ERP
CRM
Availability Group
ERP
CRM
Availability Group
ERP
CRM
Availability Group
Asynchronous
Synchronous
Windows Cluster
Node

12. AlwaysOn Availability Groups
Synchronous-commit mode
Primary replica send transaction log changes to a secondary replica
Secondary replica applies the changes in the log to its copy of the database and sends an acknowledgement to the primary replica
Primary replica commits the transaction

13. AlwaysOn Availability Groups
Asynchronous-commit mode
Primary replica send transaction log changes to a secondary replica and then commits the transaction
Secondary replica applies the changes in the log to its copy of the database

14. AlwaysOn Availability Groups
Offload workload with Active Secondary Replicas
Near-real-time reporting from replicas
Read-only routing to readable replicas
Offload Full and Log Backups to replicas
No differential and copy_only full backups

15. AlwaysOn Availability Groups
Failover options
Automatic failover
No data loss
Planned manual failover
Forced manual failover
Possible data loss
Use the Start Failover Wizard to initiate manual failover
Don’t use Failover Cluster Manager to initiate failover

16. AlwaysOn Technologies

17. Solution Example 1 Existing architecture FCI for HA
Failover Clustering
SAN
User and Application Access
Production Environment
Production Server
Passive Node
MPLS
Disaster Recovery Environment
DR Server
Log Shipping
Existing architecture
FCI for HA
Log Shipping for DR
Requirement to test DR every 6 months

18. Solution Example 1 New architecture AG with auto-failover for HA
Synchronous Replica
User and Application Access
Production Environment
Primary Replicas
Sync Replicas
MPLS
Disaster Recovery Environment
DR Server
Async Replicas
Asynchronous Replica
Automatic Failover
New architecture
AG with auto-failover for HA
Async replicas for DR

19. Solution Example 1 DR can be tested easily
Synchronous Replica
User and Application Access
Production Environment
Primary Replicas
Sync Replicas
MPLS
Disaster Recovery Environment
DR Server
Async Replicas
Asynchronous Replica
Automatic Failover
DR can be tested easily
Make async replicas sync and initiate failover
Configure new auto- failover partner and remote async
Solution can run from DR and still have DR capabilities

20. Peer-to-Peer Replication
Solution Example 2
Failover Clustering
SAN
Website Users
Web Production Environment (Hosted)
Web Production Server
Passive Node
MPLS
HQ Production Environment (On-Premises)
HQ Production Server
Peer-to-Peer Replication
User and Applications
Scale out solution with P2P replication
FCIs for HA
Requirement to simplify by removing multi-site write capability
Still need the data in HQ for reporting

21. Async Replica for Reporting
Solution Example 2
Synchronous Replica
User, Web, and Application Access
Web Production Environment (Hosted)
Primary Replicas
Sync Replicas
MPLS
HQ Production Environment (On-Premises)
Data Warehouse
Asynchronous Replica
Automatic Failover
Async Replica for Reporting
SSIS
File Share Witness
AG with autofailover for HA
Async replica back to HQ for reporting
Node vote for async replica removed
File share witness added

22. Solution Example 3 Failover Cluster Instances for HA SAN replication
Databases attached during DR
Requirement to remove dependency on SAN replication due to cost
Failover Clustering
SAN
Production SQL Server
SAN Replication
DC 2
DC 1
Production Site ( Network)
Disaster Recovery Site ( Network)

23. Availability Group Replica
Solution Example 3
Failover Cluster Instances for HA
Asymmetric storage
Asynchronous Availability Group Replica for DR
File share witness added
Votes removed from DR
Production Site ( Network)
DC 1
SAN
Production SQL Server
File Share Witness
Availability Group Replica
Failover Clustering
Disaster Recovery Site ( Network)
DC 2
SAN
Production SQL Server
File Share Witness

24. Designing a High-Availability Solution
Summary
Log Shipping
Windows Server Failover Clustering
AlwaysOn Failover Clustering
AlwaysOn Availability Groups
Advanced deployment scenarios