The Sun CD works fine with NetBSD. 

Sun modified the CD drive so that it sent 512 byte blocks over the
SCSI bus rather than 2048 byte blocks (2048 is the physical block
size). This was done because the (installed base of) Sun PROMs only
boot off media with 512 byte blocks. Unfortunately Sun have never
upgraded their PROMs (or SunOS) to cope with other block sizes.

386BSD (whose SCSI driver I have hacked on) coped with strange block
sizes by asking the device for some geometry information. This piece
of code was upto several lines long. I have no idea why it is so hard
for SunOS 5 to cope with the idea of asking a device what its block
size is.

[Disclaimer: I don't know why Sun does anything, I am only guessing.]
-- 
Lloyd Parkes, Postmaster and Hostmaster for Victoria University
"For my confession they burned me with fire
 And found that I was for endurance made." - The Arabian Nights, trans. Haddawy