When setting up Dual Write, you need to make sure that you have PFDIR2 and PFDATA2 set in the configuration file.
An example would be:
PFDATA2=K:
PFDIR2=\fpmirror
or
PFDATA2=\\w.x.y.z\sharename or \\server\sharename
PFDIR2=\fpmirror
On NIX platforms you could have this in your config file:
PFDATA2=
PFDIR2=/backup/mirror
Then you need to make sure that the path for those variables (including the filepro directory) is set up prior to activating a dual write.
In the first example it would be the path of K:\fpmirror\filepro or for NIX /backup/mirror/filepro Note that filePro needs read and write permissions.
Then, in Define Files, select the filename that you wish to mirror. Press O for Options.
Press ENTER to get to the last field: Mirror data from this file: Enter Y and then press SAVE to record.
When you SAVE to exit ddefine, it will copy all instances of data, key, index, and blob to the filename located in the mirror path.
This process edits the header of the map to include the trigger for filePro to know this is a dual write or mirrored file.
IMPORTANT NOTE: If during normal operations within a mirrored file the path to the mirror becomes unavailable, filePro will detect the error and popup a message warning the user that the mirror has been suspended. Someone will at this point need to reestablish the mirror path and then resync the files that have been suspended. Within each filePro directory there is a new file called 'mirror.xml' which contains the mirror status. The format is:
<fileProMirrorInfo>
<Mirror Status='STATUS' When='2015-12-28T23:20:58' User='USERNAME' />
<Reason>REASON FOR MESSAGE</Reason>
</fileProMirrorInfo>
Where STATUS is either 'off, 'paused', 'on', or 'resync' (See doresync)
DO NOT mirror an alien or ODBC file.
%LOCALAPPDATA%\fptech\fpmirrorwarn contains the flag for warning an end user that there is a problem.