IBM has beta drivers for the Adaptec AIC7870.ADD, AIC78U2.ADD and AICU160.ADD on their testcase site.
>From the readme.txt "These are BETA TEST ONLY drivers to resolve issues with long chkdsk and with geometry problems with Adaptec SCSI cards and ZIP drives. Use at your own risk!"
URL: ftp://testcase.boulder.ibm.com/ps/fromibm/os2/newadaptec.zip
As the readme states, use these at your own risk. Also be aware that rarely does anything stay on IBM's testcase site for more then 2-3 days, so if you think you want these get them now.
I have installed the beta AIC7870.ADD driver on a system with a builtin 7870 UW-SCSI controller and have had no problems in the past 3 hours. I have done some very limited testing concerning the slow CHKDSK on boot problem. Hopefully the followingt table is readable. Both partitions tested are HPFS.
Source: OS2VOICE