The files in an index bucket that contain the metadata that the indexer uses to search the bucket's event data. The main index files are the tsidx files, but the bucket contains a number of other metadata files as well.
The event data itself is contained in the rawdata file. The rawdata file and the index files together constitute the files in a bucket.
In an indexer cluster, a searchable copy of a bucket contains both index files and a rawdata file. A non-searchable copy contains only the rawdata file.
For more information
In Managing Indexers and Clusters of Indexers: