Applies To:
  • CitectSCADA 1.00, 1.01, 1.10, 1.11, 1.20, 2.00, 2.01
Summary:
Citect runtime has a feature that allows for redundancy of the file server. The parameter [CtEdit] Backup specifies a backup project path. If Citect cannot find a file in the normal project directory, ie the one specified by the [CtEdit] Run parameter, it will look in the backup path. If the file is found in the backup path, Citect will assume that the run path has failed (ie the file server has failed). Citect will then try the backup path first for all other files. When Citect changes over to the backup path, it will generate the hardware error 'File server failed, to Standby' and also call event number 11.

For file server redundancy to operate correctly, you cannot have any include projects - including the default include project. Copy any files that Citect will use at runtime from these project directories into your Run directory. Citect Version 1.XX does not use any files from these directories, so there is no problem with this version. Citect Version 2.XX uses libraries (*.CTL) in the Include project so copy *.CLT from the Include project into your Run directory.

File server redundancy will only operate correctly if the redirector (or shell) on the computer can handle a failure of the file server. The shell with Novell Netware cannot do this and will cause Windows to fail with fatal Network errors - when the file server fails. Microsoft LAN manager based networks and peer to peer networks will allow for this error correctly. Therefore Citect file server redundancy will operate correctly with these networks.

Also note that as only Citect will switch to a backup path, any other applications that are using files on the file server will fail when the filer server fails. This may cause the computer to wait for long periods of time for the filer server (or to crash). This includes Windows itself, so you should install Windows on a local drive.  

Solution:
To enable the file server redundancy, set the parameter to a backup database path: For example, if your primary path is F:\CITECT\USER\DB, set the backup path to another file server or a local drive:

[CTEDIT]
RUN=F:\CITECT\USER\DB
BACKUP=C:\CITECT\USER\DB

You should always make sure that the project in the backup path is the same as the one in the run directory - each time you compile the project in the run directory you should copy it into the backup directory. 
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