The top-level organizational structure in Microsoft Index Server, containing the master index and other persistent indexes. The Index Server catalog is located by default in the directory %systemdrive%\inetpub\catalog.wci, but this can be overridden during installation. Index Server is included in the Microsoft Windows NT Option Pack (and the Windows 2000 Server CD) and is usually installed along with Internet Information Server (IIS) in Windows NT 4.0 or Internet Information Services in Windows 2000 to support the indexing of Web content for IIS.
If you are hosting more than one virtual server on an IIS machine, and these virtual servers represent different companies, you might want to create multiple catalogs for Index Server, one for each virtual server. Each catalog will then be used for indexing a specific virtual server, and queries based on a catalog will return only results for content on the associated virtual server.
An Index Server query can span only one catalog at a time, so don’t create multiple catalogs unless you want to completely separate the indexing of their documents—for example, if you are hosting Web sites for multiple companies on your server.
The maximum size of the index for Index Server is 40 percent of the size of the documents being indexed (the corpus), so it is important when installing Index Server to locate the catalog on a drive with sufficient free space. For example, if you will be indexing 10 GB of documents, you will need about 4 GB of space for locating your catalog.