This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
It turns out that the SCSI drivers that come on the Sys 6.0.1 Install Disk downloaded from ftp.apple.com are incompatible with CMS ver 3.0 (and probably earlier) SCSI cards. What I did was to replace scsi.manager and scsihd.driver in the System 6.0.1 Install disk SYSTEM/DRIVERS folder with scsi.manager, scsihd.driver, AND CMS.driver from the CMS Utility disk. With the replacement scsi drivers installed, the Install disk recognizes the hard drive and installation went smoothly from that point. (The CMS files are dated 1989 and 1990, so they are a bit older than the 6.01 files, which are dated 1993. But, they work!) By: Gary Black