Working with Multiple Versions of SQL Server

Microsoft SQL Server 2005 supports multiple instances of the Database Engine, Microsoft SQL Server 2005 Analysis Services (SSAS), and Microsoft SQL Server 2005 Reporting Services (SSRS) on the same computer. You can upgrade previous versions of SQL Server, or install SQL Server 2005 on a computer where previous SQL Server versions are already installed.

You can also run a SQL Server 2000 failover cluster instance in a side-by-side configuration with a SQL Server 2005 failover cluster instance. For more information about side-by-side failover cluster instances of SQL Server, see The Microsoft SQL Server support policy for Microsoft Clustering.

Using SQL Server 2005 Side-By-Side with Previous Versions of SQL Server

You can install SQL Server 2005 on a computer already running instances of a previous SQL Server version. If a default instance already exists on the computer, SQL Server 2005 will be installed as a named instance.

Important   For SQL Server 2005 installations in side-by-side configurations with previous versions of SQL Server, SQL Server 2005 services must use accounts found only in the global domains group. Additionally, accounts utlized by SQL Server 2005 services must not appear in the local Administrators group. Failure to comply with this guideline will result in unexpected security behavior.

Side-by-side support is as follows:

1The 32-bit editions of SQL Server are supported in WOW64 only on the X64 versions of 64-bit operating systems. The 32-bit editions of SQL Server are not supported in WOW64 on the IA64 versions of 64-bit operating systems.

See Also

Tasks

How to: Install SQL Server 2005 (Setup)

Reference

Hardware and Software Requirements for Installing SQL Server 2005

Concepts

Using Upgrade Advisor to Prepare for Upgrades

Other Resources

Upgrading to SQL Server 2005
Backward Compatibility

Help and Information

Getting SQL Server 2005 Assistance

Change History