If you experience problems when using a narrow SCSI CD-ROM drive on the internal wide interface, disable "negotiate wide," "negotiate sync," or both for that device in the Adaptec configuration utility.
If you experience problems when using the narrow internal connector, then disable "de-selection" in the Adaptec configuration utility.
The Fujitsu narrow disk (M1603SAU) has been observed reselecting with an invalid queue tag ID. This is a violation of the SCSI protocol and it causes the cadp driver to behave erroneously. Because this is difficult to guard against, it is best to disable tagged queuing for these targets.
Use the iostat -E command to determine if you have a Fujitsu M1603S-512 disk. If you do, edit the /kernel/drv/cadp.conf file and add the property target n -scsi -options=0x1f78, where n is the target number.
The IBM external wide disk (DFHSS2W, Revision 1717) is not supported.