🚀 go-pugleaf

In article <36c419fe.0@glitch.nildram.co.uk>,
	"Jeremy Brooks" <jem@datasecurity.co.uk> writes:
> I see a lot of partitions where the partition table and the boot sector
> sector length appears to be either 1 or 2 cylinders longer than the actual
> disk (as detected by the BIOS).
> 
> Perhaps this is a miscalculation by the Windows/DOS install routine.
> 
> I see this an awful lot when fix hdds (i.e. partition table data against
> BIOS CHS values).
> 
> Example:
> 
> int 13h get disk info returns
> 
> 995,31,63     (disk has 2007936 sectors)
> 
> but partition table says
> 
> 128    6    0,1,1 - 996,31,63     63      2009889
> 
> and boot sector bpb.huge_sector_count = 2009889
> 
> or
> 
> 128    6    0,1,1 - 997,31,63     63      2011905
> 
> and boot sector bpb.huge_sector_count = 2011905
> 
> Could it be that this disk has this problem and the disk has become full and
> scandisk or DOS is trying to r/w these non-existent clusters (i.e. the last
> or penultimate cylinder).
> 
> This may or may not be the source of the problem, but in any event I would
> be interested to hear of anyone who knows why this happens (and it happens
> an awful lot).

  There *used* to be a system where drives had a 'spare' cylinder for
various purposes.  This *could* be the source of this problem.

  Regards,
     Harry.