Business Continuity for Virtual SQL Servers David Klee Founder – Heraflux Technologies #ITDevConnections

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 #ITDevConnections

“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? #ITDevConnections

Session Agenda Availability & Virtualization Backups High Availability Disaster Recovery Disaster Avoidance #ITDevConnections

Virtualization backups Point of Contention Virtualization backups #ITDevConnections

VM Backups Reads & Writes Reads OS Data Log OS’ Log’ Mem Copy Backup TempDB OS’ Data’ Log’ TempDB’ Mem Copy Backup Changed Blocks #ITDevConnections

“App Aware” Backup Impact #ITDevConnections

VM Backup Impact VM backups should not hurt availability Might hurt performance App-aware backups Work with VM admins to tune #ITDevConnections

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 #ITDevConnections

SLAs Point-in-time recovery? DB-level recovery? Restoration complexity? Document RPO & RTO & MTTR Validate! #ITDevConnections

Virtualization availability Complementary, not competing Virtualization availability #ITDevConnections

SQL Server Availability Traditional Options Failover Clustering “Always On” Availability Groups Mirroring Replication #ITDevConnections

Virtualization HA (Average failover time: 2m 45s) #ITDevConnections

Virtualization HA Is… Unplanned outage last resort OS restarts SQL Server starts up No protection for planned outages Complementary to SQL Server HA #ITDevConnections

Placement Two-Node WSFC #ITDevConnections

(Anti-)Affinity Rules Two-Node WSFC #ITDevConnections

Failure Domains #ITDevConnections

Architectural Considerations SQL Server & VM HA #ITDevConnections

Documented Expectations Unplanned outage Planned outages Patch management Upgrades Written vs. business expectations #ITDevConnections

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) #ITDevConnections

WSFC Heartbeat Reduce sensitivity (get-cluster).SameSubnetDelay = 2000 (get-cluster).SameSubnetThreshold = 20 (get-cluster).CrossSubnetDelay = 2000 (get-cluster).CrossSubnetThreshold = 20 (get-cluster).RouteHistoryLength = 20 #ITDevConnections

Isolate Traffic Streams Additional network adapters Dedicated VLANs? WSFC heartbeat AG replication Backups #ITDevConnections

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 #ITDevConnections

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Best Practices Complementary technologies Do what you always do! Work with VM admins Get access into hypervisor Validate everything #ITDevConnections

Competing, or complementary? Disaster recovery #ITDevConnections

SQL Server Options Traditional Options Failover Geo-Clustering “Always On” Availability Groups Mirroring (Deprecated 2012) Replication Log shipping #ITDevConnections

VM Options Replicate VM-level backups VM block-level replication Replicate DB backups VM block-level replication SAN LUN-level replication #ITDevConnections

Strategy What are your SLAs? Current DR architecture RPO RTO Databases Rest of infrastructure #ITDevConnections

Pick Best Tool for the Job VM or SQL Server DR? #ITDevConnections

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 #ITDevConnections

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 #ITDevConnections

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 #ITDevConnections

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 #ITDevConnections

Fail-Back Fail-over is only half the challenge How to handle fail-back? #ITDevConnections

Testing Test frequently Full failover & failback Best DR strategy ever… #ITDevConnections

VM-level DR might replace SQL Server DR #ITDevConnections

Where we all should be heading… Disaster Avoidance #ITDevConnections

Disaster Avoidance Multiple DCs No disruption in service “Active-Active” #ITDevConnections

Topology Speed & latency between DCs Data loss expectations VS. reality Speed of failover Compute capacity #ITDevConnections

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 #ITDevConnections

Conclusions VM HA is complementary VM DR might replace SQL Server DR Test & validate strategy Failover & failback #ITDevConnections

Questions? @kleegeek davidklee.net heraflux.com linkedin.com/in/davidaklee #ITDevConnections

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