DAT tape drive

[Popi Havaki]

 Hello, I am looking for a 4mm  DAT backup tape drive compatible with
our Suns and RS6000 machines. I have no experience on DAT 4mm tape drives.
Can anyone compare the 8mm and 4mm tape drives ? 
 Also, I need companies' name that produce DAT backup tape drive (address,fax or
phone number). I will appreciate any information .
  
                                     Thanks in advance
                                      Popi Havaki
                                     System administrator
                                     FORTH, Research Center of Crete
                                     Computer Center

                                e-mail : havaki at iesl.forth.gr