DOCUMENT ID:  1176-02

SYNOPSIS:     SCSI and VGA controllers claiming full compatibility

OS RELEASE:   2.1

PRODUCT:      Solaris x86

KEYWORDS:     SCSI VGA controllers compatibility MDB boot hard drive 


SYMPTOMS:

System may not boot from the hard drive after installation and may
report errors if using the MDB boot diskette to boot from the hard
drive. 


DESCRIPTION:

Some controllers which claim to be compatible SCSI controllers may only
be compatible at the BIOS level.  Since UNIX rarely uses BIOS after the
kernel has loaded, this "compatibility" extends only to Operating
Systems that use BIOS services, like DOS. 


SOLUTION:

If you are using a controller that claims full compatibility with one of
those listed on the Solaris X86 Hardware Compatibility Guide, also check
to make sure that the sector translation scheme used is identical as
well.  Some Adaptec-compatible controllers, for example, map the drive
to 255 heads thus affording a low cylinder count, whereas the true,
listed controller will instead map the drive geometry to 64 heads, 32
sectors/track, which is more along the lines of what the SCSI driver is
looking for.  Likewise, certain VESA Local Bus controllers will claim
full compatibility with their EISA and ISA counterparts, when this is
usually not the case. 


DATE APPROVED: 10/10/95