Building Highly Available Systems with SQL Server™ 2005 Robert Rea Brandon Consulting

Availability What does it mean to you?  Why not?  Site is unavailable  System is unavailable  Database is unavailable  Database is partially unavailable  Table is unavailable  Data is unavailable Can your customers get done, what they need to get done, when they need to do it? 24x7x365

Improved Data Availability without Requiring Standby  Downtime is reduced and/or prevented for these barriers:  Database is partially unavailable  Table is unavailable  Data is unavailable

Barriers to Availability Isolated Failures  Continuing to work with isolated failures  Limiting the scope of failure  Partial Database Availability  Online Piecemeal Restore  Supporting Technology  Instant File Initialization  How do they work?

What happens when…  Disks Fail  In SQL Server™ 2000  Database is marked suspect  Users are unable to access the database  In SQL Server™ 2005  Filegroup is marked offline  Users are able to access undamaged data

What happens when…  Recovery begins  In SQL Server™ 2000  Database is in a restoring state  Users are unable to access the database  File needs to be recreated and zero initialized  File Restore can proceed – offline  In SQL Server™ 2005  Filegroup is in a restoring state  Users are able to access undamaged data  File can be recreated with instant file Initialization  Piecemeal Restore can proceed – online

How is This Possible?  Fine grained operations are based on “functional partitioning”  Partitioning – in this sense – does not require Partitioned Tables  Partitioned Tables benefit significantly from fine grained operations  Partitioning for fine grained operations requires secondary, non-primary data files where data is strategically placed  Recovery of your damaged devices can be prioritized and then the database can be brought online in stages

Improving Data Availability Partial Database Availability

What happens when…  Indexes need to be rebuilt  In SQL Server™ 2000  Index rebuilds require an exclusive table-level lock, resulting in offline rebuilds  Users are unable to access the table  In SQL Server™ 2005  Rebuilds of an index can be performed online if a few simple criteria are met  Users are able to access the table

Online Index Operations Improving Concurrency during Index Maintenance  SQL Server™ 2000  Offline Index Rebuilds ; table data is unavailable during operation  Rebuild options: DBCC DBREINDEX and CREATE with DROP_EXISTING  SQL Server™ 2005  Includes all of the above offline operations, plus…  New ALTER INDEX…REBUILD:  ONLINE – allows concurrent user access (queries as well as modifications) to the index during rebuild  OFFLINE – works using locks (same as SQL Server™ 2000)  If online is not possible by default, consider design alternatives to fully leverage online index rebuilds

Online Index Rebuilds

What happens when…  Readers and Writers desire the same data  In SQL Server™ 2000  Locking is used to guarantee the intended level of isolation  Users must wait to access locked data  Concurrency and performance compromised  Correctness is compromised when lower isolation levels are used to avoid locking  In SQL Server™ 2005  Locking OR Versioning can be used to guarantee a variety of isolation levels  With versioning, Readers won’t block writers and writers won’t block readers  Performance improved if contention was primary bottleneck  Correctness is not compromised due to use of lower isolation levels

Snapshot Isolation Improving Concurrency in Mixed Workloads  SQL Server™ 2000  Isolation implemented solely through locking  Mixed workloads may experience:  Concurrency problems due to blocking  The Inconsistent Analysis problem  SQL Server™ 2005  Isolation implemented using locking and versioning  Mixed workloads can improve read consistency and performance using:  Read committed with Statement-level snapshot to improve statement-level consistency  Snapshot Isolation to improve transaction-level consistency

Snapshot Isolation

Barriers to Availability This job would be great if it weren’t for… …the users …the staff …us People I’m going to modify this data…right … here !

Barriers to Availability  Microsoft SQL Server™ 2005 gives you greatly improved tools to overcome these barriers to availability:  Database Server Failure or Disaster  Isolated Disk Failure  Data Access Concurrency Limitations  Database Maintenance and Operations  Availability at Scale  User or Application Error Many more barriers than discussed Only some are addressable by database technology Be sure to consider people, planning, procedures and training

Summary  SQL Server™ 2005 offers greater availability – immediately  Many technologies available just by upgrading!  Some architected/implemented over time  SQL Server™ 2005 is more Available  Partially damaged databases remain available  Databases being recovered remain available  Instant File Initialization, Fast Recovery  New and Improved Replication Alternatives  SQL Server™ 2005 is more Robust

Customer Deployments Gary Melvin, Brandon Consulting

Customer Focus – BoS (Ireland)  The Business Challenge  Management information reporting limitations  SQL 2005 Benefits  SQL Reporting Models  Ad Hoc Reports  Scheduled Reports – Multiple Formats "Having completed our evaluation of SQL 2005 we are very excited about many of the new features in SQL 2005 particularly Integration services and Reporting services. We plan to incorporate SQL 2005 into our reporting environment over the next 12 Months“ Peter Brady IT Director Bank of Scotland Ireland

Customer Focus - ADM  Business Challenge  Data From Multiple Systems And Formats Required For Reporting.  SQL 2005 Solution  Data warehousing and Reporting Solution  Integration Services  Multiple Formats Data Imports and Translations  Web Reporting “We are planning to standardize all our data requirements using SQL 2005" Noel Galligan IT Dept ADM

Customer Focus – Lifestyle Sports  Business Challenge  High Availability and Disaster Recovery  SQL 2005  Increased Performance and Reliability  Disaster Recovery  Mirroring and Replication “SQL 2005 will give lifestyle the level of performance and reliability required to run our business“ AM Keady Lifestyle Sports Operations

Customer Focus- Europa General  Business Challenge  Enterprise Information Reporting  SQL 2005 Solution  Integration Services  OLAP – Database Design  Scheduled Reporting  Add Hoc reports  Web based Reporting  "Having concluded that our current reporting system would restrict our growth, we recognised that to thrive in a very competitive market, it was critical to our business to have technology that would enable us to grow. Brandon Consulting, using Microsoft’s SQL 2005, is enabling us to consolidate our reporting across our offices, at the same time as making us a more agile & responsive business."  Brian McGrady IT Manager Europa General

© 2005 Microsoft Corporation. All rights reserved. This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.