IBM RISC600-7248: Boot failure on SCSI: Timeout / Resetting

[Harald Arnold <listen@arnold.at>]

When I start on installation process with CD 1 my IBM 7248 
RISC 6000 with debian V 3.0r2 I always get the same error 
message repeating till power off:

SCSI host 0 abort (pid 4) timeout-resetting
SCSI bus is being reset for host 0 channel
mcr53c8xx_reset: pid 4 
  reset_flags=2 serial_number=XXX serial_number of timeout=XXX

(XXX is incrementing with each message)

This message is repeated hundres of times ...

Dear helpers what can I do

Thanks Harald