Connorhd is right, everything was stored in the database in the first attachment mod, now the data is stored on disk, so I've needed to create an update script that will update the old mod to the new one ... so it will be compatible with the old one, so, no worries about loosing data (as long as you backup before trying to upgrade ) (the update script will take the old table data, and put the data onto a file, and put in the info about it in the new table 'version')
And also, this new way of storage will help ease backups ... as one only need to fetch new files (if attachments are deleted, the database entry is removed, and the file on disk is shrunk to 0 bytes... but the file is still there, so that no new attachments will use the same filename = only need to download new files when making backups )
And, if someone would like to make FTP storage instead of filestorage, I think it won't be that hard (need to replace one function for saving the attachment, and the script that downloads it needs to be fiddled with ... )... but I won't make it