sql 2005 high availability

SQL Server 2005 Administration, Scalability and Reliability

Dr Greg Low

Readify

[email protected]

Prerequisite Knowledge

• Basic T-SQL Syntax (SELECT, UPDATE)

• Experience executing stored procedures• Knowledge of how SQL Server uses transaction logs

and the SQL Server recovery process• Knowledge of SQL Server 2000 concurrency controls

Level 200Level 200

Who Am I?• SQL Server & .NET Consultant with Readify• Director of White Bear Consulting• Microsoft MVP for .NET• INETA User Group Relations Chair for Asia-Pacific• President of Qld MSDN User Group• President of Qld SQL Server User Group

Agenda

• Barriers to availability• Database server failure or disaster• User or application error• Data access concurrency limitations• Database Partitioning

Barriers to AvailabilityOverview

• Business requirements– Time and location– Processes– Expectations

• Technology– Hardware– DBMS software– Application software

Barriers to Availability Primary Server or DBMS Barriers

• Database failure or disaster– Hardware failure– Human-made disaster– Natural disaster

Barriers to Availability Primary Server or DBMS Barriers

• User or application error– Accidental data modifications– Malicious data modifications

• Data access concurrency limitations– Multiple transactions accessing same data– Persistent data structure changes

Agenda


Database Server Failure or Disaster Overview

• Failover clustering• Database mirroring• Now many alternatives available

– Peer to peer replication (new)– Standard replication topologies– Log shipping– Backup and restore– Detach, copy, attach

Database Server Failure or Disaster Failover Clustering• Provides a hot standby• Built on Microsoft Cluster Services (MSCS)

– Multiple nodes (Now 8)– Automatic failover of instance (~20 seconds)– Certified hardware required

• Zero committed work loss• Single copy of instance databases• Standby not available for any other use• Supports more SQL services

MS-2087 Implementing Microsoft Windows 2000 Clustering

Database Server Failure or Disaster Failover Clustering

Shared Disk ArrayShared Disk Array

22ndnd Private ‘Heartbeat’ network Private ‘Heartbeat’ network

Clustered ServersClustered Servers

ClientsClientsVirtual ServerVirtual Server

Primary NetworkPrimary Network

Database Server Failure or Disaster Database Mirroring• Provides a hot standby (instant)• Database failover

– Very fast automatic failover (less than 3 seconds)– Transparent client redirect

• Zero committed work loss• Some performance impact• Maximum one mirror for each database• Standby not directly available for any other use

MS-2733 Updating Your Database Administration Skills to Microsoft SQL Server 2005

Database Server Failure or Disaster Database Mirroring Hardware

• No special hardware required– Requires a second server– Servers do not need duplicate hardware

• Virtually no distance limitations– No shared disk arrays– Transaction latency requirements determine acceptable

network latency


Database Server Failure or Disaster Database Mirroring With Automatic Failover

Separate Disk ArraysSeparate Disk Arrays

Principal ServerPrincipal Server

Mirror ServerMirror Server

ClientsClients

Witness ServerWitness Server

Database Server Failure or Disaster Database Mirroring With Automatic Failover

Configuring and Using a Database Configuring and Using a Database MirrorMirror

demonstrationdemonstration

User or Application Error Comparison of High Availability Options

Feature

Hot Standby Warm Standby Cold Standby

Database Mirroring

Failover Clustering

Peer-to-Peer

Transactional Replication

Log Shipping

Backup /

Restore

Detach / Copy / Attach

Data LossNo data loss

optionNo data loss

Some Data Loss possible

Some data loss possible



Some data loss

likely

Automatic Failover

Yes Yes Optional No No No No

Transparent to Client

Yes, Auto-Redirect

Yes, Reconnect to

same IPOptional No, NLB helps

No, NLB helps

No No

Downtime

< 3 Seconds20 Sec + DB

RecoveryNone Seconds

Seconds + DB Recovery

Detect, Restore, Manual failover

Detect, Attach, Manual failover

Standby Read Access

Continuously accessible Snapshot

NoContinuously

accessibleContinuously

accessibleIntermittently accessible

No No

User or Application Error Comparison of High Availability Options

Feature

Hot Standby Warm Standby Cold Standby

Database Mirroring

Failover Clustering

Peer-to-Peer Replication

Transactional Replication

Log Shipping

Backup/ Restore

Detach/ Copy/ Attach

Data Granularity

Database Only

All System and User

DatabasesTable or View Table or View

Database Only

Database Only

Database Only

Masks Disk Failure

YesNo, Shared

DiskYes Yes Yes Yes Yes

Special Hardware Needed

No, Dup. system needed

Specialized Hardware from

Cluster HCL






Complexity Some More More More More Some Some

Agenda


User or Application Error Database Snapshots• Read-only• Static view of database• Transaction consistent at point of time• Does not store all data pages• Reads only original data pages

– Reads data from snapshot if data has changed– Reads data from database if data has not changed

• Increases disk I/O of source database


User or Application Error How Database Snapshots Work

User or Application Error Database Snapshot Scenarios

• Enabling mirroring database for reporting• Historical point-in-time reporting• Recovering from administrative error• Protecting against application or user error

Implementing and Using Database Implementing and Using Database SnapshotsSnapshots


Agenda


Data Access Concurrency Limitations Pessimistic Concurrency Controls

• Default Setting and Behavior• Designed for Data Integrity• SELECT Operations Require Shared Resource Locks• Different Isolation Levels Control Behavior of Shared

Locks

MS-2072 Administering a Microsoft SQL Server 2000 Database

Data Access Concurrency Limitations Optimistic Concurrency Controls

• Optional setting and behavior• Implemented using row versioning• Designed for data integrity but allows reads of

committed data• SELECT operations do not require shared resource

locks• Different isolation levels control behavior of

committed reads

Data Access Concurrency Limitations Row Versioning

• Several Uses– Triggers for Inserted and Deleted tables– Multiple Active Result Sets (MARS) sessions– ONLINE Index Operations– Optimistic concurrency controls (row snapshots)

• Versions built in tempdb for all modified rows• Versions deleted when no remaining transaction or

operation needs them

Data Access Concurrency Limitations Snapshot Isolation Level

• Reads committed data at time of transaction start• ALLOW _SNAPSHOT_ISOLATION database option• TRANSACTION ISOLATION LEVEL SNAPSHOT

session option

Data Access Concurrency Limitations ONLINE Index Operations

• Table accessible for reads and modifications during ONLINE index operations

• Existing non-clustered indexes available to optimize during ONLINE clustered index operations

• Non-clustered index is not available during its index operation

Data Access Concurrency Limitations ONLINE Index Operation Commands

• CREATE INDEX• ALTER INDEX• DROP INDEX• ALTER TABLE

– ADD or DROP of UNIQUE index– ADD or DROP of PRIMARY KEY with CLUSTERED index

option

Agenda


Database Partitioning

• Designed for:– VLDB with very large tables (ie 100’s GB)– Large systems with 8, 16, 32 or more “real” CPUs

• Replace partitioned views where partitions are in a single database

Database Partitioning

• Partition Function – each row of a table is assigned to a partition (ie 1, 2, 3…)

• Currently only a single column but workaround with persisted calculated columns

• Partition Scheme – each partition for a partition function is mapped to a filegroup

Implementing and Using Database Implementing and Using Database PartitionsPartitions


Session Summary

• Several new features available in SQL Server 2005 to protect against server failure

• Database snapshots can be used to protect against application, user, or administrative error

• Use the new optimistic concurrency controls and ONLINE index operations to reduce database contention issues

For More Information

• Visit TechNet at www.microsoft.com/technet

Microsoft LearningTraining Resources for IT Professionals

To see the detailed syllabus or to locate a training providerTo see the detailed syllabus or to locate a training providerplease visitplease visit

www.microsoft.com/learning

Course Title Available


Now

MS-2734 Updating your Development skills to Microsoft SQL Server 2005 Database

Now

MS-2087 Implementing Microsoft Windows 2000 Clustering

Now

http://www.microsoft.com/learning

SQL Server 2005 2 Day Workshops

• Microsoft SQL Server 2005 Database Infrastructure & Scalability,

• presented by Brent Challis, DDLS

• Microsoft SQL Server 2005 Business Intelligence,

• presented by Peter Myers. Tenix Connections

• Microsoft SQL Server 2005 Development,• presented by Greg Low, White Bear Consulting

SQL Server 2005 Workshops• Cost $650 and $575 for early birds. • For Schedule, Registration and further

information

– Partners only http://www.microsoft.com/australia/partner/training/

– Customers and Partners: http://www.microsoft.com/australia/events/sql2005 (This page will be available later this month)

http://www.microsoft.com/australia/partner/training/

http://www.microsoft.com/australia/events/sql2005

SQL Server 2005 Workshops

• Register Now for Yukon Workshops

Microsoft Partner can register for all 3 workshops at www.microsoft.com/australia/partner/training/default.aspx

Microsoft Customers can register for all 3 workshops at• com.au/YukonCusBI

• com.au/YukonCusDev

• com.au/YukonCusAdmin

Workshops run nationally and are scheduled between 7 March and 30 June 2005, places are limited so be quick.

http://www.microsoft.com/australia/partner/training/default.aspx

User Community

• SQLServer.org.au (Australian SQL Server User Group)

• Sign up and attend your local user group!• SQL Server 2005 Beta 2 Kit:

– http://msstore.datacom.com.au/sqlbeta– 3 CD/DVDs

• SQL Server 2005 Beta 2• SQL Server 2005 Resource Kit• SQL Server 2005 Presentations (videos)

http://msstore.datacom.com.au/sqlbeta

Code Camp• Code Camp Oz is happening 23/24th April at

Charles Sturt University in Wagga Wagga• Be there!• www.codecampoz.com

http://www.codecampoz.com/

The SQL Server 2005 University Masters

•Fully accredited, masters level degree from Charles Sturt University

•SQL Server 2005 MCDBA certification included as an integral component

•Graduates eligible for full professional level membership of the Australian Computing Society

•Part time study delivered via Distance Education

•Qualifies for Government FEE-HELP program

•Places available for experienced applicants without previous qualifications

First intake commences September 2005Register your interest at www.itmasters.info

http://www.itmasters.info/

http://www.csu.edu.au/courses/pg/sci/m_nsa

Where Can I Get Help?• Free chats and webcasts

www.microsoft.com/technet/community/chatswww.microsoft.com/technet/community/webcasts

• List of newsgroupswww.microsoft.com/technet/community/newsgroups

• Microsoft community siteswww.microsoft.com/technet/community

• Community eventswww.microsoft.com/technet/community/events

• Community columnswww.microsoft.com/technet/community/columns

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