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A Beginners Guide to HADR

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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

6

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


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