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Clustering versus Always On Support:the battle
Peter Borremans,Integration Domain Lead & Architect
@PeterBorremans
Agenda
• Why do you need HA?• SQL Clustering• SQL Always On Introduction• BizTalk 2016 and Always On• The choice
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VMWare HA
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➔ Regular snapshots needed to cover software faults➔ Finding a valid snapshot and restoring it takes time➔ Data Loss
➔ Protection against hardware failures
➔ No patching without downtime possible
➔ No protection if patching goes wrong
HA with Clustering or Always On
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➔ Specific knowledge required
➔ Protection against hardware and software failures (SQL)
➔ Application level awareness
➔ Data protection
➔ Patching node by node (no downtime)
➔ Patching gone bad can be fixed
BizTalk HA on a SQL Cluster
➔ Only HA solution until and including BTS 2013 R2
➔ Based on Windows Failover Clustering
➔ Shared storage necessary➔ Single copy of data
➔ Single instance and network name
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BizTalk SQL Clustering
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Active Node Passive Node
Instance 1 (Tracking)
Instance 2 (Runtime)
Shared Storage
BizTalk SQL Clustering
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Active Node Passive Node
Shared Storage
Instance 1 (Tracking)
Instance 2 (Runtime)
Passive Node Active Node
BizTalk SQL Clustering
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Active Node Active Node
Shared Storage
Instance 1 (Tracking)
Instance 2 (Runtime)
Cluster & Licensing
➔ True passive => no license
➔ SQL Standard Edition can be used for a 2 node failover cluster
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Concepts
Availability GroupAutomatic Failover
Availability Replicas
Availability
Databases
Always On
Secondary Backups
Readable Secondaries
Windows Server Failover Cluster
Listener
Primary Replica
Asynchronous Commit
BizTalk HA with Always On
➔ New since BizTalk 2016
➔ Windows Failover Clustering is still used!➔ SQL Group Listener
➔ Local storage is sufficient
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Always On Shared storage
➔ No shared storage required
➔ Use a FileShare witness location for quorum
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BizTalk 2016 Always On Support - Why?
➔ Microsoft Azure IaaS does not support shared storage➔ This excludes SQL Clustering
➔ This excludes Application level HA for BizTalk Server
➔ SQL Always On is supported in Azure IaaS➔ Application level HA for BizTalk Server
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BizTalk SQL Always On
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Primary Replica Secondary Replica
Instance 1
Instance 3
Local Storage
Instance 2
Instance 4 Instance 3
Instance 2
Instance 4
Instance 1
Local Storage
Secondary Replica Primary Replica
Always On AG protection
➔ A database is protected (by moving log blocks)➔ Sync mode
➔ Async mode
➔ Multiple databases can exist in one group
➔ Group concept opens features as in clustering➔ Virtual identity (listener)
➔ Programs should talk to a listener
➔ No shared resources! (storage for example)
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Failover
➔ Manual failover➔ Failover to an ASYNC secondary might cause data loss!
➔ Failover to a SYNC secondary will never cause data loss.
➔ Automatic failover
➔ BizTalk Server requires SYNC mode
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BizTalk with Always On support
➔ BizTalk 2016
➔ SQL 2016
➔ Windows➔ Windows 2012 R2 with hotfix #3090973
➔ Windows 2016
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Software requirements
Why 4 SQL Instances per node?
➔ MSDTC➔ No distributed transactions in one SQL Server Instance
➔ Spread databases across instances
➔ Instances can be on the same server (VM)
➔ 4 listeners
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BizTalk Instances with Always On
Instance # Instance Name Databases
1 Authentication SSODB
2 Management BizTalkMgmtDb
3 Runtime BizTalkMsgBoxDbBizTalkRulesEngineDbBAMPrimaryImportBAMStarSchemaBAMAlertsApplication
4 Tracking BizTalkDTADb
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BizTalk 2016 Always On Limitations
➔ Replicate Logins and SQL Agent jobs
➔ Modify SQL Agent jobs to run on primary
➔ No Read-Only routing➔ Backups on primary
➔ SQL Server Analysis Services and SQL Server Integration Services do not participate in Availability Groups➔ BAM depends on this
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Licensing
➔ “Advanced availability” (Always On) requires a SQL enterprise license
➔ If the secondary is truly passive (no reports, backups, …) no license is required
➔ A licensed primary only covers one passive secondary (if additional secondary's are added, these should be licensed)
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Licensing 2
➔ Basic Availability Group on Standard Edition➔ https://msdn.microsoft.com/en-
us/library/mt614935.aspx?f=255&MSPPError=-2147217396
➔ Maximum 2 replicas (one primary / one secondary)
➔ No read access on secondary
➔ Only one DB per AG => ugly setup
➔ Cannot be upgraded to advanced AG
➔ Basic AG support a Group Listener
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Make your choice
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Clustering Always On
Cost + -
Complexity of the setup - -
Preference by DBAs - +
Shared Storage - +
BizTalk version support + -
Azure IaaS HA support - +
HA for SSIS / SSAS + -
ConceptsNo solution is ‘best’
Evaluate the required Service Level
Choose the technology fit for purpose
Involve necessary skills
Thank you!
Keep in touch. Call or mail. Ask questions. Happy to help.
+32 473 337 335
@PeterBorremans
www.linkedin.com/in/peterborremans