SQL Server 2012 - AlwaysOn

Joo Loureiro

Microsoft

About Joo Loureiro

SQL Server Senior Support Escalation Engineer (3rd tier support level)

Bridge between frontline support and SQL product group

SQL Server Denali TAP Escalation Engineer (part of SQL Server Beta program)

Blog: http://blogs.msdn.com/joaol (joaol@microsoft.com)

Engaged on Service Packs, hot fixes and new product releases.

SQL Server High Availability Retrospective

SQL Server High Availability Today Enterprise customers are being successful

Dell, HP, Bwin, ServiceU, CareGroup, BigHammer

but Solutions fragmented

Lack important flexibility points

Initiated holistic review of SQL HA and DR Looked at customer scenarios (RTO and RPO requirements, Local HA

and DR)

Enterprise blockers

Mission Critical Needs (online ops, patching, planned and unplanned maintenance)

Failover requirements and hardware usage

Future needs

Mission Critical High Availability Solution

Meets mission

critical high

availability SLA Integrated Efficient Flexible

AlwaysOn Availability Groups

AlwaysOn Availability Groups is a new feature that enhances and combines database mirroring and log shipping capabilities

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

A Flexible Solution

AlwaysOn provides the flexibility of different HA configurations

Synchronous

Data Movement

Asynchcronous

Data

Movement

Shared Storage, regional and geo secondaries

A

A

A

A

A

Direct attached storage local, regional and geo target

A A

Mission Critical

Requirements

Zero data loss is critical for the

business

Fast application recovery during

planned and unplanned

downtime

Redundancy across 3

datacenters

Application databases and

dependencies failover together

Deploy using AlwaysOn Availability

Groups

demo

Application Failover

Availability Groups Listener allow applications to failover seamlessly to any secondary Application reconnects using a virtual name after a failover to a

secondary

AG_HR

HR

DB

HR

DB

Primary Secondary HR_VNN

-server HR_Listener;-catalog HRDB

Application retry during failover

Connect to new primary once

failover is complete

and the listener is online

Primary Secondary Secondary

HR

DB

ServerA ServerB ServerC

What about Server Objects?

Introducing Contained Databases or CDBs

Unit of application programmability in Denali

A DB which establishes a boundary between application and server

CDBs sever the userlogin relationship

Windows users no longer need matching logins

Users with passwords replace SQL logins

CDB can be part of an availability group and can failover across replicas

Authentication information moves with the CDB

Limitation Other objects, like jobs are not contained and has to be managed

Availability Group Architecture

Inter-node health detection,

Failover coordination,

Primary health detection,

Distributed data store for settings and state,

Distributed change notifications

Windows Server Failover Cluster

WSFC Common Microsoft Availability

Platform

Database

Active Log Synchronization

Database

Active Log Synchronization

Availability Group uses Windows

Server Failover Cluster (WSFC) for

AlwaysOn Active Secondary

IT efficiency and cost-effectiveness is critical for businesses

Idle hardware is not an option anymore

AlwaysOn Active Secondary enables efficient utilization of

high availability hardware resources thereby improving

overall IT efficiency

Active Secondary can be utilized for

Balancing read-only workloads

Offloading Backup Operations

Readable secondary allow offloading read queries to secondary

Close to real-time data, latency of log synchronization impact data freshness

DB2 DB1

SQLservr.exe SQLservr.exe

InstanceA

DB2 DB1

Primary Secondary

InstanceB

Reports

Primary Secondary

Reports

Active Secondary Making Secondary Readable

Read-Only Client Connectivity

Read-Only client connection behavior determined by Availability Replica Option+ ApplicationIntent Property

ApplicationIntent is a connection property

Replica option determines whether a replica is enabled for read access when in a secondary role

Read-Only Routing enables redirection of client connection to new secondary on role change

Enable seamless redirection of application connection across replicas without manual intervention

Concurrency and Blocking REDO can get blocked by reporting workload REDO thread and read workload can deadlock

Solution Internally map read workload to non blocking isolation levels (no application

changes required) Read Uncommitted Snapshot Isolation Read Committed Snapshot Isolation Repeatable Read Snapshot Isolation Serializable Snapshot Isolation Ignore all locking hints

Never choose REDO as deadlock victim

Result Blocking and deadlock between Reporting workload (i.e. Query) and REDO

thread is eliminated

No issues with DML (INSERT/DELETE/UPDATE) as it is not allowed Will incur additional cost of row versioning.

Read Workload Impact

Readable Secondary

demo

Active Secondary Enabling Backup on Secondary

Backups can be done on any replica of a database

Backups on primary replica still works

Log backups done on all replicas form a single log chain

Database Recovery Advisor makes restores simple

R/W workload

Primary

Backups

Secondary

Backups

Secondary

Backups

Restrictions, cautions, and gotchas

Differential backups are not supported on secondary

Only Copy-only full backups are supported on secondary

The only distinction is the differential bitmap clearing

Advisable for backups to be stored centrally

Backup from Secondary

demo

Key Enhancements

Fast instance failover through predictable

database recovery time

Native support for multi-site

clustering across subnets enable DR

using failover

cluster instances

Flexible Failover Policy

Eliminates false failover

Configurable failure condition levels

Better diagnostics

SMB support enables consolidation of

more than 26 instances

Support TEMPDB on local drive

Introduce Flexible Failover Policy

Flexible Failover Policy provides administrators control over the

conditions when an automatic failover should be initiated.

Diagnostics

Configurable options eliminate false failover

Improved logging for better diagnostics

Reducing Planned Downtime

Support for Windows Server Core

Reduce OS patching by as much as 50-60%

Support for rolling upgrade and patching of SQL Server for both Availability Groups and Failover Cluster Instance

Fast failover time for both Availability Groups and Failover Cluster Instances

New online operations supported

LOB Index

Adding of column with default

KB 976097 - Hotfix to add support for asymmetric storages to the Failover Cluster Management MMC snap-in for a failover cluster that is running Windows Server 2008 or Windows Server 2008 R2

Supports SQL Server Failover Cluster Instances with AlwaysOn Availability Groups

KB 2494036 - A hotfix is available to let you configure a cluster node that does not have quorum votes in Windows Server 2008 and in Windows Server 2008 R2

Supports configuring optimal quorum with non-automatic failover targets

All nodes should be in the same AD domain

To create WFSC cluster user running creation must have: Domain account Administrator on all machines Have Create Computer objects and Read All Properties rights in AD

Detailed Article: http://technet.microsoft.com/en-us/library/cc731002(WS.10).aspx

Windows Server Pre-Reqs

Quorum: need majority of votes to operate and avoid split brain

Two-Steps process: 1. Select nodes to vote (KB 2494036)

1 vote if nodes that host a replica that is currently: Primary (if primary is an FCI include all possible owner nodes for that FCI) An auto failover target if the primary is also configured for auto failover

0 votes for rest of nodes

2. Select the quorum type: Odd number of votes, use Node Majority Even number of votes, add a witness by either:

Adding an additional witness node and use Node Majority Using Node and File Share Majority with a protected file share (blog with

details)

Re-evaluate and adjust quorum after manual failover outside automatic target

Quorum Configuration

Disaster Recovery

demo

A

A

A

A

Reports

Backups

Synchronous

Data Movement

Asynchcronous

Data

Movement

New Topology

Denali AlwaysOn Resource Center: http://msdn.microsoft.com/en-us/sqlserver/gg490638(en-

us,MSDN.10)

RCO download (available soon)

Documentation

MSDN forums

Microsoft Connect

AlwaysOn Blog

Resources Links

SQL Server 2012 Highlights

High

Availability

SQL Server AlwaysOn

Security &

Manageability

User-Defined Server Roles

Web &

Breadth

PHP Driver

Scalability &

Performance

Distributed Replay

Application Centric Failover

Contained Database Authentication

Local DB Runtime

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 Group

Windows 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

Intelligence

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

Thank You

2008 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.

The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market

conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation.

MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.