[This is preliminary documentation and subject to change]

# About the Metabase

The metabase is a hierarchical store of configuration values used by IIS that incorporates rich functionality such as inheritance, data typing, change notification, and security. The metabase configuration for IIS 4.0 and IIS 5.0 was stored in a proprietary binary file, and was not easily readable or editable. IIS 6.0 replaces the proprietary binary file called metabase.bin, with plain text XML formatted files called MetaBase.XML and MBSchema.XML.

The benefits of XML formatted plain text metabase files are as follows:

- The metabase files can be edited directly using common text based tools
- Improved troubleshooting and metabase corruption recovery
- Improved backup/restore capabilities on machines that experience critical failures
- metabase Schema can be extended by an administrator using ADSI
- 100% compatibility with IIS 5.0 metabase API's and ADSI
- Improved performance and scalability

## The metabase files can be edited directly using common text editing tools

The text based XML metabase allows administrators to easily read and edit the metabase files directly without having to use scripts, code, or the IIS snap-in to administer IIS. For more information, see About Editing the MetaBase.xml File While IIS Is Running.

## Improved troubleshooting and metabase corruption recovery

The XML metabase eases diagnosis of potential metabase corruption because the metabase is stored in a plain-text files that can be easily read using common text based tools such as Microsoft Notepad and compared using tools like the Windows Resource Kit utility Windiff. As the metabase is edited and saved, IIS makes versioned copies of the MetaBase.XML and MBSchema.XML files in a The Metabase History Feature. The history files can be used to compare changes that were made to MetaBase.XML.

## Improved backup/restore capabilities on machines that experience critical failures

The backup and restore capabilities of IIS 6.0 have improved over IIS 5.0 by allowing an administrator to back up the metabase with an administrator password. This allows the metabase to be restored on a different computer or a different installation of Windows Whistler in the event of a critical failure. Additionally, the metabase can be restored with a previous version of the Metabase.XML and or MBSchema.XML file from the history folder. For more information, see Metabase Reliability.

## Metabase Schema can be Extended by an Administrator

The XML metabase uses schema to enforce what properties can be written, and at what locations in the metabase the properties can be written, as well as enforcing the data types that can be used for a particular attribute. The schema can be extended using ADSI so that custom applications can store information in the metabase. For more information, see Metabase Schema.

## 100% compatibility with IIS 5.0 metabase API's and ADSI

Because the XML metabase is fully compatible with IIS 5.0 metabase API's and ADSI, existing scripts and code will continue to work. For more information about the interfaces to the metabase, see About Configuring the Metabase.

## Improved performance and scalability

The new XML metabase improves performance and scalability. The new XML metabase has:

- Comparable or better disk footprint size to the IIS 5.0 metabase.
- Faster read times on Web server startup than the IIS 5.0 binary metabase.
- Equivalent write performance to the IIS 5.0 binary metabase.

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