1. Business Continuity for Virtual SQL Servers
David Klee
Founder – Heraflux Technologies
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2. Founder & Chief Architect
About David Klee
@kleegeek
davidklee.net
heraflux.com
linkedin.com/in/davidaklee
Specialties / Focus Areas / Passions:
Performance Tuning
Virtualization & Cloud
Business Continuity
Health & Efficiency
Capacity Management
Founder & Chief Architect
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3. “How can I work with my infrastructure team to avoid outages?
“I fight with my infrastructure teams on my SQL Server availability strategy”
…. should become ….
“How can I work with my infrastructure team to avoid outages?
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4. Session Agenda Availability & Virtualization Backups High Availability
Disaster Recovery
Disaster Avoidance
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5. Virtualization backups
Point of Contention
Virtualization backups
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6. VM Backups Reads & Writes Reads OS Data Log OS’ Log’ Mem Copy Backup
TempDB
OS’
Data’
Log’
TempDB’
Mem Copy
Backup
Changed
Blocks
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7. “App Aware” Backup Impact
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8. VM Backup Impact VM backups should not hurt availability
Might hurt performance
App-aware backups
Work with VM admins to tune
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9. Tran Log Management Most VM backups do not manage tranlogs
DON’T let them say you don’t need it!
SQL Server tranlog mgmt required
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10. SLAs Point-in-time recovery? DB-level recovery?
Restoration complexity?
Document RPO & RTO & MTTR
Validate!
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11. Virtualization availability
Complementary, not competing
Virtualization availability
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12. SQL Server Availability
Traditional Options
Failover Clustering
“Always On” Availability Groups
Mirroring
Replication
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13. Virtualization HA
(Average failover time: 2m 45s)
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14. Virtualization HA Is… Unplanned outage last resort OS restarts
SQL Server starts up
No protection for planned outages
Complementary to SQL Server HA
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15. Placement
Two-Node WSFC
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16. (Anti-)Affinity Rules
Two-Node WSFC
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17. Failure Domains
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18. Architectural Considerations
SQL Server & VM HA
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19. Documented Expectations
Unplanned outage
Planned outages
Patch management
Upgrades
Written vs. business expectations
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20. Time Sync “Time drift” Sync with AD Do not sync with host
Verify 15 min (or less) sync period
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient\SpecialPollInterval (seconds)
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21. WSFC Heartbeat Reduce sensitivity (get-cluster).SameSubnetDelay = 2000
(get-cluster).SameSubnetThreshold = 20
(get-cluster).CrossSubnetDelay = 2000
(get-cluster).CrossSubnetThreshold = 20
(get-cluster).RouteHistoryLength = 20
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22. Isolate Traffic Streams
Additional network adapters
Dedicated VLANs?
WSFC heartbeat
AG replication
Backups
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23. Validate Network Perf Shared-everything environment
Synchronous drags if network slow
Use iperf to test network throughput
iperf.fr
How-To Guide: hfxte.ch/iperf
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25. Best Practices Complementary technologies Do what you always do!
Work with VM admins
Get access into hypervisor
Validate everything
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26. Competing, or complementary?
Disaster recovery
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27. SQL Server Options Traditional Options Failover Geo-Clustering
“Always On” Availability Groups
Mirroring (Deprecated 2012)
Replication
Log shipping
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28. VM Options Replicate VM-level backups VM block-level replication
Replicate DB backups
VM block-level replication
SAN LUN-level replication
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29. Strategy What are your SLAs? Current DR architecture RPO RTO Databases
Rest of infrastructure
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30. Pick Best Tool for the Job
VM or SQL Server DR?
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31. DR Site Primary Site SQL Server VM A SQL Server VM A WAN
15 minute block-level replication
WAN
SQL Server VM B
SQL Server VM B
60 minute block-level replication
Virtualization
Virtualization
DR Site
Primary Site
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32. Primary Site DR Site SQL Server FCI VM A FCI VM B SQL Server FCI VM A
Virtualization
Consistency Group
Asynchronous LUN-level replication
Virtualization
DR Site
Primary Site
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33. DR Site Primary Site SQL Server VM A SQL Server VM C WAN
5 minute transaction log replication
WAN
SQL Server VM B
SQL Server VM D
60 minute transaction log replication
Virtualization
Virtualization
DR Site
Primary Site
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34. WSFC DR Site Primary Site AG01 SQL Server VM A SQL Server VM C WAN
Async DB replication
SQL Server VM A
SQL Server VM C
WAN
Sync DB repl
SQL Server VM B
SQL Server VM D
Async DB replication
Virtualization
Virtualization
DR Site
Primary Site
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35. Fail-Back Fail-over is only half the challenge
How to handle fail-back?
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36. Testing Test frequently Full failover & failback
Best DR strategy ever…
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37. VM-level DR might replace SQL Server DR
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38. Where we all should be heading…
Disaster Avoidance
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39. Disaster Avoidance Multiple DCs No disruption in service
“Active-Active”
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40. Topology Speed & latency between DCs Data loss expectations
VS. reality
Speed of failover
Compute capacity
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41. WSFC Secondary Site Primary Site AG01 AG02 SQL Server VM A
Sync DB replication
SQL Server VM A
SQL Server VM C
WAN
AG02
SQL Server VM B
SQL Server VM D
Async DB replication
Virtualization
Virtualization
Primary Site
Secondary Site
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42. Conclusions VM HA is complementary VM DR might replace SQL Server DR
Test & validate strategy
Failover & failback
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43. Questions? @kleegeek davidklee.net heraflux.com
linkedin.com/in/davidaklee
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