The default behavior of the Zebra system is to reference the records from their original location, i.e. where they were found when you ran zebraidx. That is, when a client wishes to retrieve a record following a search operation, the files are accessed from the place where you originally put them - if you remove the files (without running zebraidx again, the server will return diagnostic number 14 (``System error in presenting records'') to the client.
If your input files are not permanent - for example if you retrieve your records from an outside source, or if they were temporarily mounted on a CD-ROM drive, you may want Zebra to make an internal copy of them. To do this, you specify 1 (true) in the storeData setting. When the Z39.50 server retrieves the records they will be read from the internal file structures of the system.