SQL-Server 2012 Always On

SQL Server “SQL-Server 2012” HighlightsHigh

Availability

SQL Server AlwaysOn

Security & Manageabili

tyUser-Defined Server Roles

Web & Breadth

PHP Driver

Scalability &

Performance

Distributed Replay

Application Centric Failover

Contained Database Authentication

Local DBRuntime

Fast FILESTEAM

UTF-16

Readable Secondaries

Fast Full-Text Search

Reliable, Integrated Failover Detection

Multiple Secondaries

Audit Enhancements

Paging for result sets

Column Store Index, “Apollo”

HA for StreamInsight

Management Pack for High Availability

Backup Secondaries

JDBC 4.0 driver

Support for ARM processors

Active Directory w/ SharePoint for SSRS

Default Schema for Windows GroupWindows

Server Core Support

Beyond Relational

FileTable

Microsoft Project “Juneau”

Online Operations

Win32 Access to Database files

Semantic Search Platform

Full Globe Spatial Support

DAC Enhancements

ODBC for Linux

Fast Spatial Performance

Hybrid Applications with SQL Azure

> Up to 15K Partitions/Table

> EIM

> SSIS Server

> Business Intellige

nce

> Unified Semantic Model

> Crescent > Data Quality

> Alerting

> Enhanced MDS

> In-memory BI for corporate

> Sysprep for AS

> PowerPivot Enhancements

> Reporting as SharePoint Shared Service

> DBC & OLTP Appliances/RAs

> MDS add-in for Excel

What is Always On Availability Group

Recommended HA for database availabilityBest features of Mirroring

Non Shared StorageFast FailoverAutomatic Page RepairSupport for High Latency Networks

Plus new featuresFailover Group of databasesMultiple secondary replicasReadable secondary replicasVirtual names for fast failoverMore flexible failover policyIntegration with traditional Failover Clustering

AlwaysOn Availability Groups

AlwaysOn Availability Groups is a new feature that provides availability for application database(s).

• Provides protection from planned and unplanned downtime

Multi-database failover Multiple secondaries

Total of 4 secondaries 2 synchronous secondaries

1 automatic failover pair

Synchronous and asynchronous

data movement Built in compression and

encryption Automatic and manual

Failover Flexible failover policy Automatic Page Repair

Application failover using virtual name

Configuration Wizard

Dashboard System Center

Integration Rich diagnostic

infrastructure File-stream

replication Replication

publisher failover

>Flexible

>Integrated

>Efficient Active

Secondary Readable

Secondary Backup from

Secondary

Automation using power-shell

Case Study – Dell DVD Store Enterprises

Need to accept 24 x 7 transactionsFor High Availability

Zero down time and data loss (automatic)SLA to cover storage failure“I see web site unavailable and you are fired”

“Reporting” Near real time. No more than 1 minute behindWith minimal impact on live transactions

Disaster RecoveryHave second data centre. No more than 30 mins down time and 5 minutes data loss

UpgradeAny upgrade needs to be with no down time or data loss

Typical HA/DR/Reporting Architecture

DR Site

Application Server(s)

SQL-Server 2012 Always On

Application Server(s)

Reports

Backup

> SAN> SAN

> Reports

Backup

RéplicaRéplica

RéplicaRéplica

RéplicaRéplica

> éplica> éplica

Installation

Always On relies on WSFC Always On is NOT a clustered install of SQLDoes not need Shared DiskWindows 2008 Server+ EE neededNeed to Enable HadrService

Via configuration managerOr via PowerShell

Some Patches and QFE NeededKB 976097KB 2494036  

Migrating to Always On / SQL-Server 2012

Any normal migration is possible:Backup / RestoreAttach / DetachMirroringLog ShippingReplication

Might need some post migration tasksCompatibilityUse of new features such as Containment

Quorum ChangesRequired for automatic failoverBuilt in feature of WSFCReplaces the concept of “witness” to avoid split brainTwo recommended Steps

1. Select nodes to vote2. Select the Quorum Type

If Odd number use “Node Majority”If even number use “Node Majority plus File Share Witness”

Requires QFE KB KB 2494036  to enable Voting

May need to adjust quorum after failover outside automatic target

Secondary Replica Features

FailoverBackup \ DBCCReporting QueriesAlwaysOn AutoStat Automatic Page Repair

Secondary Replica – Active Log Sync

Log Cache

Log Cache

Secondary read is behind primaryLog is first hardened and then applied

Redo thread is asynchronous and runs in the backgroundLatency (typically seconds) can be larger for log intensive operations like bulk import or index create/rebuildSync Replica minimizes latency due to network issues

DB1

DB1 Log

DB1

Log Capture Log

Recieve

DB1 Data

Redo Thread

Redo Pages

DB1 Log DB1 Data

Page Updated

Log HardenLog Flush

Commit

Acknowledge Commit

Log Pool

Network

Availability Groups and Failover Cluster InstanceAvailability Groups integrates

seamlessly with AlwaysOn Failover Cluster Instance

Failover Cluster Instance used for local high availability

Availability Groups provide ability to failover to a disaster recovery site

> Automatic failover of the availability group is disallowed when one of the replicas is an FCI

AlwaysOn Resources“SQL-Server 2012” AlwaysOn Resource Center: http://msdn.microsoft.com/en-us/sqlserver/gg490638(en-us,MSDN.10)

DocumentationMSDN forumsMicrosoft ConnectAlwaysOn Blog