SCSI: Apple Supports Both SCSI Group 0 and Group 1

I understand that computers that use SCSI Group 0 set of commands on drives larger than 1.073742 gigabytes will, when they reach the 1.073742 limit, wrap around to the beginning of the disk, overwriting the first blocks.

I am also told that the SCSI Group 0 set of commands is in some Sun Microsystems -- and virtually ALL Apple -- operating systems.

If this is true, what is the solution if I want to have these large capacity drives? Are the vendors of these large drives responsible for
providing a solution?
Apple's "driver" (software installed to the drive during HD SC Setup and uploaded to the memory during system boot) can be set up to use either 6 bytes (Group 0) or 10 bytes (Group 1) SCSI commands. Although they are using 6 bytes command currently, if the capacity of our drives goes beyond 1.2GB, then the driver can be changed to use Group 1 commands for those drives.

The Macintosh OS can allow different drivers to exist at the same time, so we don't have to change the driver for the current drives, just add the new driver when necessary. Incidentally, our current drives support both group 0 and group 1 commands, too.

Our driver currently supports Group 0, but can easily be modified to support Group 1 when necessary.

Note: Apple's driver only supports Apple hard drives. Third-party hard drives require their own drivers.
Published Date: Feb 18, 2012