The disk space you need for an index depends on the size and type of data you want to index. As a guide, for indexing single-byte documents you need to reserve disk space of about 0.7 times the size of the documents you want to index. For double-byte documents, reserve the same disk space as the size of the documents you want to index.
The amount of space needed for the temporary files in the work directory is 1.0 to 4.0 times the amount of space needed for the final index file in the index directory.
If you have several large indexes, you should store them on separate disk devices, especially if you have concurrent access to the indexes during index update or search.
You must also specify the directory where you will store the text index. Ensure that there is enough disk space and that the DB2 instance owner has write access to the directory.