I have a tekram scsi controller (trm0).  In 1.6 I had no problems w/ it,
In 2.0 its fine on the 1st boot after power-cycle, but after a reboot, 
I get:
  trm0: parity error
  sd1(trm0:0:0:1:0) generic HBA error.

whenever I try to access, sd1, and device not configured to disklabel 
/dev/sd1 , etc.
If I boot into 1.6, it works fine, but boot back into 2.0 and the 
problem comes back, unless I power-cycle -- reset-button is not enough. 
  The drive is configured to /not/ spin up initially, if that matters.  
It's been going on for a while, judging from the logs, but as I don't 
mount the drive automatically, I only noticed this weekend.

sd0 is a atapi-zip
sd1 is  ultra-star 18 <IBM, DXHS, 0430>