Re: Ahah, 4096 blocksize disk is not recognised under Linux?

[Geert U. <ge...@li...>]

On 10 Jan 2003, Kulwant Bhogal wrote:
> The thing that puzzles me is that the Seagate specs for the drive
> (http://www.seagate.com/support/disc/specs/scsi/st34573lc.html) (lw [mine] is also
> on this page) bear no resemblance to the HDToolbox numbers even after
> accounting for the 4096 blocksize. Examples are number of tracks: 37,505,
> cylinders: 7,501, heads physical: 5, disks (3.5 inch): 3. 
> The number of sectors is not too far out at 8,888,924 (/8 = 1,111,116). 
> (Seagate numbers). 
>  
> HDToolbox states that there are 3 heads. 
> 
> I suspect that HDToolbox does it's own interpretation of the drive geometry
> - which also happens to work (somehow!!). Actually I am surprised that it
> actually all works - well it works as long as you don't want to reformat to a foreign
> (to AmigaOS) disk format!. 
> 
> But for Linux, I am not sure where that leaves us. 

Don't worry. In contrast to IDE devices, SCSI devices are always accessed by
specifying linear sector numbers (for IDE you have CHS and LBA). So it doesn't
matter how many heads you fake to have, as long as you specify the correct
linear sector number it'll work. HdToolBox probably just tries to find optimal
CHS values so you can use as much of the disk as possible (i.e. find C, H, and
S such that (numsectors-C*H*S) is minimal).

BTW, even on IDE devices the CHS values don't correspond to the real number of
heads etc.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@li...

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds