1. A Beginners Guide to HADR
Warwick Rudd
A Beginners Guide to HADR

2. Warwick Rudd @Warwick_Rudd Warwick@sqlmastersconsulting.com.au
Blogger on SimpleTalk
Speaker at TechEd Australia
Speaker at Ignite Australia
Speaker at Ignite New Zealand
Speaker at Difinity New Zealand
Speaker at SQL Saturday events
Speaker at Local User Groups
Host DBA Fundamentals DownUnder VC
Host DBA DownUnder VC
@Warwick_Rudd

3. SQL Server Always On: The Senior DBA’s Field Guide
Master Class Training
SQL Server Always On: The Senior DBA’s Field Guide
Edwin Sarmiento
Data Platform MVP
Microsoft Certified Master
Where - Microsoft Brisbane
When – February 26-28, 2018
In Person – AU$1, GST
Online – AU$1, GST
Bonus US$ material included
2 for 1 Offer

4. High Availability and Disaster Recovery (HA/DR) planning is not just about the technology.
When thinking or talking about High Availability/Disaster Recovery, many people jump straight to a particular technology without understanding other factors impacting the solution, and then waste time working backwards to understand requirements.
Recovery Objectives, SLA’s and budget are some of the commonly overlooked factors when planning and developing a HA/DR solution. In this session we will walk through the 6 building blocks I take into account when developing a HA/DR solution.
You can then use this same methodology to implement High Availability &/or Disaster Recovery in your own environment, working forward to determine the right technology.
Abstract

5. By the end of this session you will understand the 6 building blocks to use in designing and implementing a HA/DR solution for your SQL Server environment.
Not picking a technology first.
Goals

7. High Availability &recovery Disaster Recovery

8. Accidental DBA’s?
DBA’s ?
DB Developers?
BI Developers?
Team Leaders / Managers?
Project Managers?
Randoms?

9. What is High Availability ?
“A system design approach associated service implementation that ensures a prearranged level of operational performance will be met during a contractual measurement period”
“The principal goal of a high availability solution is to minimize or mitigate the impact of downtime. A sound strategy for this optimally balances business processes and Service Level Agreements (SLAs) with technical capabilities and infrastructure costs”
Microsoft -

10. What is Disaster Recovery ?
“A system and set of processes that allow returning a system to a state of normality after the occurrence of a disastrous event”
“The principal goal of a disaster recovery solution is to resume as close to normal activity in a pre-defined amount of time as outlined by Service Level Agreements (SLAs)”

11. Determining a HA/DR Solution
9’s Downtime
SLA’s
$$$
SKILL
Recovery Point Objective (RPO)
Recovery Time Objective (RTO)
Recovery Level Objective (RLO)
Technology

12. Un-Scheduled Down Time
What is Down Time ?
Scheduled Down Time
DB Maintenance
Failovers
Patching
System Configurations
Upgrades
Consolidations
Un-Scheduled Down Time
Failovers
Hardware Failures
Loss of Network Connectivity
Power Outages
Database corruption

13. Down Time Nines Availability % Downtime / Day HH:MM:SS
Downtime / Month
Downtime / Year 90
02:24:00
73:02:55
876:34:55 99
00:14:24
07:18:17
87:39:30
99.9
00:01:26
00:43:50
08:45:57
99.99
00:00:09
00:04:23
00:52:36
99.999
00:00:01
00:00:26
00:05:16
00:00:00.1
00:00:03
00:00:32
Nines

14. Recovery Point Objective
“Is the maximum targeted period in which data might be lost from an IT service due to a major incident”
Wikipedia -
“In Database terms how many minutes or hours worth of data loss is acceptable for the application database being considered”

15. Recovery Time Objective
“Is the targeted duration of time and a service level which a business process must be restored after a disaster (or disruption) in order to avoid unacceptable consequences”
Wikipedia -
“In Database terms how many minutes or hours do we have to restore an application database system to normal functional operations”

16. Recovery Level Objective
“Is the targeted granularity of a system to recover in the event of a disaster (or disruption) in order to allow the system to continue normal functional operations”
“In Database terms do we need to consider things at the Instance Level, Database level or table level?”

17. Technology Capabilities
Potential Data Loss (RPO)
Potential Recovery Time (RTO)
Automatic Failover
Readable Secondaries
Availability Groups (Synchronous Commit)
Zero
Seconds
Yes
0-3
Availability Groups (Asynchronous Commit)
Minutes No
0-8
Failover Clustered Instances NA
Seconds – Minutes
Database Mirroring (High Safety)
Database Mirroring (High Performance)
Transaction Log Shipping
Minutes – Hours
Not during a restore
Virtual Machines
Azure Site Recovery
Minutes - Hours
Azure Backup
StorSimple
Cool Storage

18. Service Level Agreements
“A contract outlining the obligations to be met for predefined scenarios”
Examples:
Backup retention periods
Uptime / Downtime requirements
Recovery time requirements in the event of issue
Data corruption recovery times
HA failover times
DR failover times

19. Total Cost of Ownership (TCO)
Hosting Costs
On-premises
Cloud
Hybrid
Hardware Costs
Servers
SANS
Networking
Software Costs
Application
Database
Monitoring
Operational / Support Costs
Vendors
Business hours
After hours
Staff
Training
Holidays
Seek leave
Consultants

20. Components SQL Server Database Engine (Pretty well covered already)
SQL Server Analysis Services
Supported in a Clustered Environment
SQL Server Reporting Services
Scale-Out Deployment
Not Support FCI Environment
Supported in AGs
NLB requirement
SQL Server Integration Services
Components

21. Versions & Editions SQL Server Versions: 2005 2008 2008 R2
2012
2014
2016
VNext
Supported features by Version and Edition impacts the end design.
Required features impacts the Version and Edition required in the design.
SQL Server Editions:
Standard BI
Enterprise
Datacenter
Versions & Editions

22. Mitigations Site level loss Natural Disaster (Fire, Flood, Earthquake)
Intentional attack
Hardware level failure
Server failure
Disk failure (SAN, local disk)
Memory failure
Switch failure
Controller failure
Network level failure
Power failure
Data loss
Malicious attack
Accidental human error
Data Corruption
Mitigations

23. Capacity & Performance
“Availability and Recoverability are not the only concerns”
Things to take into consideration:
Distance between sites
Bandwidth between sites
Location of Application Servers to SQL Servers
Hardware Specifications
Network Configurations
Storage Configurations
Ability to expand or upgrade

24. Processes & Documentation
“When something goes wrong how do you respond?”
Things to take into consideration:
Failover process
Who is involved and what do they need to do?
What triggers a response?
Patching
Failover Testing
DR Testing
Data Recovery Testing

25. Backup & Recovery Recovery Models: Full Recovery Requirements: Simple
Bulk-Logged
HA/DR features will dictate the recovery models required.
HA/DR features do no solely provide protection for your data. A Backup and Recovery strategy is required to provide a complete solution.
Ties back to SLA’s mentioned earlier.
Should be tested and timed on a regular basis.
Recovery Requirements:
RPO
RTO
Backup & Recovery

26. Monitoring Things to Monitor: Server Up/Down Instance Up/Down
Agent Up/Down
Database Up/Down
SQL Error Log
Windows Event Log
Server Health
CPU Utilisation
Memory Utilisation
Disk Utilisation
Disk Capacity
Agent Job failures
Failover Events
WSFC Health
AG Health
DB Mirroring Health
Log Shipping Health
Data Transfer Rates
Redo Rates
Latency behind
Log transfer rates
Monitoring

27. Patching Server Level Service Packs Cumulative Updates Hot Fixes
Security patches
Rolling
HA Technology
Regular
Proactive Schedule
Patching

28. We looked at the definitions of High Availability and Disaster Recovery
We looked at the 6 Building blocks of High Availability and Disaster Recovery:
Down Time
Recovery Objectives
Technology
Service Level Agreements
Total Cost of Ownership
Skill
Summary

29. Thank You
Questions?

30. Thanks to all our Sponsors