On Wed, 21 Aug 1996 14:46:08 -0500 Richard Flagg said:
>Attention ADSM support and all the ships at sea!
>Anyone know what may be the problem?
>
>We just installed ADSM on AIX v4.
>We defined a lago data wheel library to ADSM.
>When we try to define the tape drives we get the following error:
>
>    ANR8420E DEFINE DRIVE: An I/O error occurred while accessing drive TAPE1.

A few things to try:

Make sure there are no other scsi devices on the same adapter at the same
  address.

Make sure you defined the device to AIX using the ADSM device driver.
  When using SMIT to define the drives, go into the ADSM sub-menu.

Make sure you have the correct element address.  Try the other one, at
  element 55, if you're not sure.

Check the AIX error log (via smit, or errpt).  It might have some useful
  info about what the I/O error actually was (since ADSM doesn't seem to
  provide anything useful).

..Paul