Create RAID device (afa0) under Redhat3

Hello !

We would like to use a Nagios plugin to monitor our RAID (hardware)
disk (on a Redhat 3 linux distribution).
This plugin uses the afacli utility.
We had first to create the afa0 device using the command :
../MAKEDEV.afa afa0
We have had the following error :
../MAKEDEV.afa: Can not derive the major number for device afa.

Note that the MAKEDEV command is just a simple sh script.

We have tried to install a up-to-date MAKEDEV rpm package (C
executable), but it requires the device path as argument.
How can we know which device (under /dev) represents our raid

Sorry for these basic questions. We have tried to google to find a
solution but without any success... :-(

Thanks in advance.