1. Planning High Availability and Disaster Recovery
Module 9
Planning High Availability and Disaster Recovery

2. SQL Server High Availability and Disaster Recovery Solutions
Module Overview
9: Planning High Availability and Disaster Recovery
SQL Server High Availability and Disaster Recovery Solutions

3. Lesson 1: High Availability and Disaster Recovery with SQL Server 2014
9: Planning High Availability and Disaster Recovery
Considerations for Implementing High Availability and Disaster Recovery
Question
You are configuring an AlwaysOn availability group to provide both high availability and disaster recovery. The availability group includes 4 servers at your main datacenter and 2 servers in the disaster recovery site at a different physical location. To which of the following servers should you not give a quorum vote?
( )Option 1: A server in the disaster recovery site that hosts a secondary replica.
( )Option 2: A server at the main datacenter that hosts a primary replica
( )Option 3: A server at the main datacenter that hosts a secondary replica
( )Option 4: A fileshare witness
Answer
(√) Option 1: A server in the disaster recovery site that hosts a secondary replica.

4. High Availability and Disaster Recovery
9: Planning High Availability and Disaster Recovery
High availability solutions are intended to prevent service outages from occurring
Disaster recovery solutions are intended to enable recovery from outages
Backups alone do not provide a comprehensive disaster recovery solution
RPO and RTO are business-driven targets that can assist with high availability and disaster recovery planning

5. 20465D
Considerations for Implementing High Availability and Disaster Recovery
9: Planning High Availability and Disaster Recovery
You should consider the following points in your high availability and disaster recovery planning:
The number of sites
The cost of maintaining idle servers for failover
Quorum configuration
Store tempdb locally to reduce I/O on shared storage
Use AlwaysOn technologies to implement high availability and disaster recovery solutions:
Multi-site Failover Cluster Instance
AlwaysOn Availability Group
Failover Cluster Instance and Availability Group in combination
Degraded availability
Test high availability and disaster recovery plans

6. Lesson 2: SQL Server High Availability and Disaster Recovery Solutions
9: Planning High Availability and Disaster Recovery
Combined AlwaysOn Failover Cluster Instance and AlwaysOn Availability Group Solution
Question
You have a SQL Server that uses the Simple recovery model. You want to ensure availability. Should you create an AlwaysOn FCI or an AlwaysOn Availability Group?
Answer
Create an AlwaysOn FCI

7. Multi-Site Failover Cluster Instance Solution
20465D
Multi-Site Failover Cluster Instance Solution
9: Planning High Availability and Disaster Recovery
Windows Server Failover Cluster
AlwaysOn Failover Cluster Instance
Primary site
DR site
Active
node
Local failover
Remote failover
Storage replication
Point out that using SAN replication will require working closely with your SAN vendor to decide the best way to present the replicated storage, and may require additional cluster-aware software to integrate intra- site storage failover.

8. AlwaysOn Availability Group Solution
20465D
AlwaysOn Availability Group Solution
9: Planning High Availability and Disaster Recovery
Windows Server Failover Cluster
AlwaysOn Availability Group
Primary site
DR site
Primary
Secondary
Synchronous
Asynchronous
File share witness

9. 20465D
Combined AlwaysOn Failover Cluster Instance and AlwaysOn Availability Group Solution
9: Planning High Availability and Disaster Recovery
Windows Server Failover Cluster
AlwaysOn Failover Cluster Instance 1
Primary site
DR site
Node A
(passive)
Node B
(active)
AlwaysOn Failover Cluster Instance 2
Node C
Node D (passive)
Availability Group primary
Availability Group secondary
Availability set

10. Lab: Planning High Availability and Disaster Recovery
Exercise 2: Plan a Solution for the Human Resources Database
This lab is a series of planning and discussion exercises. As part of each exercise, students discuss their plans with one or more other students. The purpose of this is to check that students understand their proposed solutions well enough to explain them, and to allow them the opportunity to improve their plans through discussion. To facilitate these discussions, you should allocate a partner for each student. If there is an odd number of students, you can divide into groups of three or more.
Note that for each scenario, there may be several viable solutions, and that the suggested solution is not intended to be the only correct answer.
Exercise 1: Plan a Solution for the Online Sales Database
The Online Sales database supports the company’s online sales application. Over the last few years, the online sales channel has grown to become the largest generator of revenue for Adventure Works—so the Online Sales database is a vital part of the infrastructure. The following high availability and disaster recovery solution is currently in place:
The database is hosted on a SQL Server 2008 R2 cluster instance on a two-node WSFC. The cluster is located at headquarters on the /16 network.
There is a second identical cluster that is hosted at a disaster recovery site that uses the /16 network.
Each cluster uses a SAN for shared storage, and SAN replication keeps the two SANs synchronized.
While this solution is effective and enables both high availability and disaster recovery, there are two key issues—identified by management—that your new plan should address:
Management do not feel that the investment in the SAN has been cost-effective so far. In particular, the cost of SAN replication is very high.
There are issues with the quorum configuration that have caused occasional outages in the past, and which need to be resolved.
In the new solution, local failover must occur automatically. Some data loss is acceptable on failover to the disaster recovery site.
You and a colleague will individually assess the current setup, and devise a new plan. You will then explain your plans to each other and attempt to decide on a single course of action.
Logon Information
Virtual Machine: 20465C-MIA-SQL
User Name: ADVENTUREWORKS\Student
Password: Pa$$w0rd
Estimated Time: 60 minutes
(More notes on the next slide)

11. 20465D
Lab Scenario
9: Planning High Availability and Disaster Recovery
You have been charged with reassessing the high availability and disaster recovery systems that are in use across the Adventure Works company database infrastructure. You will need to examine the current high availability and disaster recovery solutions where they exist, and suggest how they could be improved to make them more resilient, and cost-effective. Where there is no high availability or disaster recovery solution in place, you must supply an appropriate solution. For the purposes of this assessment exercise, management have not placed any specific financial constraints on your planning. Although there is an emphasis on discovering solutions that offer the best value for money, the key task at this stage is to identify the best solution for each scenario.

12. Lab Scenario (Continued)
9: Planning High Availability and Disaster Recovery
In this lab, you will examine two different scenarios and plan a solution for each one that includes both high availability and disaster recovery.

13. 20465D
Lab Review
9: Planning High Availability and Disaster Recovery
In the lab exercise, you considered various solutions for each scenario. Do you agree with the recommended solution for each scenario? If not, what would you have done differently?
Question
In the lab exercise, you considered various solutions for each scenario. Do you agree with the recommended solution for each scenario? If not, what would you have done differently?
Answer
Answers will vary, depending on students’ opinions.

14. Module Review and Takeaways
9: Planning High Availability and Disaster Recovery
Review Question(s)
Review Question(s)
Question
Think about how high availability and disaster recovery implementations work in your own organization. Can you think of any ways in which you could improve the solutions that are currently in place?
Answer
Answers will vary, depending on students’ opinions and experiences.