Index and Index Cache - Overview

The software indexes (creates a catalog of) the data that it backs up, according to that data's characteristics, such as the name of a file, or subject of an e-mail. The index improves performance during browse, analysis and recovery operations. It supplies information about backed-up files without searching through the actual backup, which is also useful for reporting.

A copy of the index is stored together with the backed-up data in the storage library. The Index Cache is a temporary working area that the SnapProtect software uses while creating an index. The index comprises multiple files that together constitute a database.

The SnapProtect software automatically maintains and manages Index Cache content. The index is automatically aged out of or brought back to this working area as necessary. If an Index Cache does not contain the required index, the software retrieves that index from storage. An index may not be in the cache if, for example, the cache area was running low on space, and the index-creation process removed inactive indexes from the working area.

Here is how the Index Cache fits into the environment:

Terminology

Catalog Catalog and Index are used interchangeably. Cataloging (indexing) the data lets you quickly browse and locate data for subsequent operations, like archiving and erasing.
Index A collection of metadata for backed-up data, created during backup, and used by find, browse, restore, and other operations.
Index Cache The temporary working area where metadata is kept while creating the index. Related to it is the Index Cache Directory, where index creation jobs place index files while the index is being built. These files are not normally deleted immediately when the job completes, but may be aged out later to obtain more working space if needed. The Index Cache directory is created on the MediaAgent by the software installation process. By default it is located in the software installation directory.