If you have an earlier version of NetWare Btrieve (such as 5.x or 6.0) installed on your system, perform the following operations before you run the NetWare INSTALL program:
Versions of Btrieve prior to 6.0x used pre-imaging to protect files from corruption in case of a system failure. Btrieve 6.x also uses this method to protect files that employ the pre-6.0x file format. NOTE: For files using the Btrieve 6.x file format, a new Btrieve 6.x page handling technique called shadow paging replaces pre-imaging, as described in Shadow Paging in Chapter 1, "Introduction to NetWare Btrieve."
Before updating a file using the pre-imaging feature, Btrieve creates a temporary pre-image file. This file, with a .PRE extensions, contains the pages to be updated from the original file. Btrieve then performs the update on the original file. If the system fails during the update, Btrieve can restore the original file using the pre-image file. If you have any extraneous pre-image (.PRE) files in your database, you must remove them before installing and starting Btrieve 6.1x. IMPORTANT: If you do not remove the extraneous .PRE files remaining from using earlier version of Btrieve before installing Btrieve 6.1x, file corruption may occur.
The following procedure explains how to check for and remove extraneous .PRE files. Note that you must have Btrieve 5.x or 6.0 loaded before performing these steps. Using your existing version of Btrieve (such as 5.x or 6.0), open the Btrieve data file corresponding to the .PRE file that you want to remove in Exclusive mode. Perform a Get First (12) operation. Perform an Update (3) operation (this will not change the first record). Close the Btrieve data file. This should delete the associated .PRE file. Any .PRE files that remain for the designated file after you perform Steps 1 through 4 are extraneous. Delete them now. Repeat Steps 1 through 5 to find and delete any other extraneous .PRE files. Once you have removed the extraneous .PRE files from your database, remove the earlier version of Btrieve from your system, as described in the following section. NOTE: If you need to preserve your Btrieve 5.x files, you can use Btrieve 6.x to read them.Checking for and Removing Extraneous Pre-Image Files