Download A Technical Overview of SQL 2005 High Availability Features

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 200
Who Am I?
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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
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•
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•
•
Barriers to availability
Database server failure or disaster
User or application error
Data access concurrency limitations
Database Partitioning
Barriers to Availability
Overview
• 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
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•
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Barriers to availability
Database server failure or disaster
User or application error
Data access concurrency limitations
Database Partitioning
Database Server Failure or Disaster
Overview
• Failover clustering
• Database mirroring
• Now many alternatives available
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–
–
–
–
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
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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
Primary Network
Virtual Server
Clients
Clustered Servers
2nd Private ‘Heartbeat’ network
Shared Disk Array
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
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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
MS-2733 Updating Your Database Administration Skills to
Microsoft SQL Server 2005
Database Server Failure or Disaster
Database Mirroring With Automatic Failover
Clients
Witness Server
Principal Server
Mirror Server
Separate Disk Arrays
Database Server Failure or Disaster
Database Mirroring With Automatic Failover
demonstration
Configuring and Using a Database
Mirror
User or Application Error
Comparison of High Availability Options
Hot Standby
Feature
Data Loss
Automatic
Failover
Transparent
to Client
Warm Standby
Failover
Clustering
Peer-toPeer
Transactional
Replication
Log
Shipping
Backup
/
Restore
Detach
/ Copy /
Attach
No data loss
option
No data loss
Some Data
Loss possible
Some data loss
possible
Some data
loss possible
Some
data loss
possible
Some
data loss
likely
Yes
Yes
Optional
No
No
No
No
Yes, AutoRedirect
Yes,
Reconnect to
same IP
Optional
No, NLB helps
No, NLB
helps
No
No
< 3 Seconds
20 Sec + DB
Recovery
None
Seconds
Seconds +
DB Recovery
Detect,
Restore,
Manual
failover
Detect,
Attach,
Manual
failover
Continuously
accessible
Snapshot
No
Continuously
accessible
Continuously
accessible
Intermittently
accessible
No
No
Database
Mirroring
Downtime
Standby
Read
Access
Cold Standby
User or Application Error
Comparison of High Availability Options
Hot Standby
Feature
Data
Granularity
Masks
Disk
Failure
Special
Hardware
Needed
Complexity
Warm Standby
Cold Standby
Database
Mirroring
Failover
Clustering
Peer-to-Peer
Replication
Transactional
Replication
Log
Shipping
Backup/
Restore
Detach/
Copy/
Attach
Database
Only
All System and
User
Databases
Table or View
Table or View
Database
Only
Database
Only
Database
Only
Yes
No, Shared
Disk
Yes
Yes
Yes
Yes
Yes
No, Dup.
system
needed
Specialized
Hardware from
Cluster HCL
No, Dup. system
needed
No, Dup. system
needed
No, Dup.
system
needed
No, Dup.
system
needed
No, Dup.
system
needed
Some
More
More
More
More
Some
Some
Agenda
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•
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Barriers to availability
Database server failure or disaster
User or application error
Data access concurrency limitations
Database Partitioning
User or Application Error
Database Snapshots
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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
MS-2733 Updating Your Database Administration Skills to
Microsoft SQL Server 2005
User or Application Error
How Database Snapshots Work
User or Application Error
Database Snapshot Scenarios
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Enabling mirroring database for reporting
Historical point-in-time reporting
Recovering from administrative error
Protecting against application or user error
demonstration
Implementing and Using Database
Snapshots
Agenda
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Barriers to availability
Database server failure or disaster
User or application error
Data access concurrency limitations
Database Partitioning
Data Access Concurrency Limitations
Pessimistic Concurrency Controls
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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
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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
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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
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Barriers to availability
Database server failure or disaster
User or application error
Data access concurrency limitations
Database Partitioning
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
demonstration
Implementing and Using Database
Partitions
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 Learning
Training Resources for IT Professionals
Course
Title
MS-2733 Updating Your Database Administration
Skills to Microsoft SQL Server 2005
MS-2734 Updating your Development skills to
Microsoft SQL Server 2005 Database
MS-2087 Implementing Microsoft Windows 2000
Clustering
Available
Now
Now
Now
To see the detailed syllabus or to locate a training provider
please visit
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)
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.
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)
Code Camp
• Code Camp Oz is happening 23/24th April at
Charles Sturt University in Wagga Wagga
• Be there!
• 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 2005
Register your interest at www.itmasters.info
Where Can I Get Help?
• Free chats and webcasts
www.microsoft.com/technet/community/chats
www.microsoft.com/technet/community/webcasts
• List of newsgroups
www.microsoft.com/technet/community/newsgroups
• Microsoft community sites
www.microsoft.com/technet/community
• Community events
www.microsoft.com/technet/community/events
• Community columns
www.microsoft.com/technet/community/columns