Free to a good home (UK) - bits!

Tue Apr 29 21:13:37 CDT 2008

On Tue, Apr 29, 2008 at 5:37 PM, Patrick Finnegan
<pat at computer-refuge.org> wrote:
> > Anyone know the details on the magic figure of 1.073GB for a MicroVAX
> > 3100?  Does that work out to being a certain logical block threshold
> > above which something breaks?
>
> Yes, it's 2^21, 512 byte blocks.  In the older SCSI command set that the
> firmware on those uses, I think that the maximum block count is 2^21 -
> 1.  Going over that may cause the firmware to overwrite the wrong part
> of the disk when it tries to do a crash dump.  Also, booting with a
> bigger disk may not work.
>

Oh, SCSI READ6 (08h) (21-bit LBA) vs. SCSI READ10 (28h) (32-bit LBA).
That makes sense now.  Thanks.