SQL Server 2012 AlwaysOn and SQLSentry
Kevin Kline• Director of Engineering Services, SQL Sentry• SQL Server MVP since 2004• Twitter, FB, LI: KEKline• Blog: http://KevinEKline.com, http://ForITPros.com
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Agenda
The Basics of
AlwaysOn
SSMS Tooling Demo
SQLSentry Tooling Demo
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The Basics
• Database-level protection• Built upon the foundation of database mirroring• Requires a Windows Server Failover Cluster.• Availability Groups (AGs) are what most people
mean when they say “AlwaysOn”
Inherits from DBM:• Sync / Async data
protection• Automatic or
manual failover• Automatic page
repair• Compressed data
stream• TCP endpoints
With WSFC:• Does NOT require
instances to be Failover Cluster Instances (FCIs)
• Does NOT require that servers start out as clustered if using standalone instances
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What Does WSFC Mean for a DBA?• You need to know WSFC very thoroughly.• Quorum matters.• Nodes must be part of the same domain. (Different
subnets are ok).• Quorum matters.• WSFC validation is very important.
• AG feature doesn’t check like in setup for FCI• It’s on YOU to check it.• %windir%/Cluster/Reports• Apply hotfixes per Windows version
• Quorum matters.
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I Know Mirroring. How’s This Different?
• Enterprise Edition only. DB in full recovery mode only.• Not a 1:1 ratio of principals to mirrors. Per AG:
• Up to 4 additional replicas, for a total of 5• Up to 3 synchronous replicas• Up to 2 automatic failover pairs
• Multiple DBs in an AG will failover at the same time.***• Easily span subnets.• Replicas usable for read-only access and backups.
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Availability Groups Fundamentals
o
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Flexible Failover Policy LevelsFailure Condition Level
On server down. This is the least restrictive level. 1
On server unresponsive. 2
On critical server error. The default level. (1 and 2, plus internal errors).
3
On moderate server error. (1 – 3, plus other errors like stack dumps). 4
On any qualified failure conditions. (1 – 4, plus other errors like worker thread exhaustion and unresolvable deadlocks).
5
Damaged databases and suspect databases?Nope, not detected by any failure-condition level.
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AG Metadata
• SSMS (in demo)• DMVs:
• sys.availability_*• sys.dm_hadr_*
• Xevents• SP_server_diagnostics: checks the health_check_timeout
value in 30 second intervals, by default.
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Additional Resources
• Plan Explorer Free: http://sqlsentry.net/plan-explorer/sql-server-query-view.asp
• Twitter and #SQLHelp
• SQLCAT.com• SQLSkills.com• Community Sites:
• SQLPASS.org• SQLServerCentral.com• SQLBlog.com• SQLTeam.com
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SUMMARY
SSMS, Traces, and Execution PlansTest Harness & TestingQuery Tuning TipsTemp tables
Cursors & LoopsNULLError HandlingTransactions
Security isn’t an afterthoughtChange Management is risk management
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Q & A
• Send questions to me at: [email protected] • Twitter, Facebook, LinkedIn at KEKline• Slides at http://KevinEKline.com/Slides/ • IT Leadership content at http://ForITPros.com
• THANK YOU!
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