RAW FTP log files are files created by the server, detailing all of the FTP activity on your server.
If your having problems with FTP then you can check these log files to see what has been going on, and what responses have been made between client and server.
If you want to diagnose connectivity issues on your server or see the raw log files, you can find them here:
WHM >> Main >> Account Functions >> Raw FTP Log Download
Alternatively, you can login via FTP to the ROOT account if your server is unclustered, and navigate to:
The rotated messages will be messages.1 ,messages.2, messages.3 and messages.4