Re: Parted CHS news... (non-512-byte sectors)

[Andrew Clausen]

On Sun, Aug 01, 2004 at 06:48:49PM -0700, John Gilmore wrote:
> > Firstly, does anyone know anything about sector sizes != 512?  I've
> > never seen one in the wild.
> 
> Many SCSI disks can be formatted to have 1024-byte sectors, or larger.
> CDROM drives (except those with Sun-modified firmware) have
> non-512-byte sectors; I think they're 2048 but don't quote me.
> 
> Whether any of these would work in an IBM PC, or with a PC BIOS, or
> with Windows, or with Linux, is a whole 'nother question.

Right... does Windows / BIOS / whatever just pretend that there are 512-byte
sectors?  According to fdisk: no, they really do support non-512 byte
sectors.  Parted does what fdisk does.

I'm concerned what might happen if Linux/Windows/BIOS all disagree about
the sector size.  Then we'd have CHS-style landmines all over again.

> Older SCSI hardware (the kind that you ran the whole-disk FORMAT
> command on; the ones that didn't come already formatted) is certainly
> capable of it.  Hmm, Andrew, I may have some of these drives around,
> that I could ship to you, if the modern SCSI drives you have access to
> can't do a non-512 FORMAT command.

Would you be able to see what the BIOS makes of it?

> I've been looking for open source software for running format commands
> and such on SCSI disks; anybody have any pointers? 

I had a look at this a while ago... the Linux kernel doesn't seem to
provide a userland interface to these commands.  (Userland can
manually send SCSI requests via an ugly ioctl, but this is nasty)

Cheers,
Andrew