Hi Eric,

I have a 3575 L12 (four B-drives) an d 3570 B02 (two B-drives) and I could
solve all of the I/O errors I have had in the past. I have upgraded all of
the 6 drives to level 4234 about 8 weeks ago.

Now, to your questions.

1.) Your can determine your current level by calling diag. Do the following
     diag
        - select "Task Selection (Diagnostics, Advanced Diagnostics,
Service Aids, etc.)"
        - select " Display Hardware Vital Product Data"
        - position to the equivalent /dev/rmtx device, hit enter (a plus
sign will then appear in fromt of the device), then hit F7 key
        - in the Viatal Product Data display you can see the drives
firmware at line "Device Specific (FW). I have 4234 for all drives.

3.) You can get the most current level form IBM's hardware support. There
is no ftp site from where you can download firmware. I have got
      the firmware from IBM here in Augsburg (Germany) on a diskette in DOS
format. So I did a dosread to my installation directory. Then I
      installed the new firmware with tapeutil (Tape Drive Service Aids).
It can also be done with diag ("Task Selection (Diagnostics,
      Advanced Diagnostics, Service Aids, etc.)", "IBM TApe Drive Service
Aids)", "Microcode load").

2.) As mentioned before, you can upgarde the formware by yourself. With
tapeutil you do the following:
     tapeutil
       - select "4. Tape Drive Service Aids"
        - select "Microcode Load"
      - position to equivalent /dev/rmtx and hit enter
      - at "Enter Filename" enter the filename of your new firmware
      - now hit F7 key
      - download of firmware to the drive begins; successful download will
      be displayed (message ?Operation completed successfully!?)
      - now hit F10 and enter q to exit tapeutil.

That's it. I hope this will help.

regards
Rainer