[2845] in linux-scsi channel archive
Re: Micropolis
daemon@ATHENA.MIT.EDU (Gerard Roudier)
Sat Nov 22 05:29:02 1997
Date: Sat, 22 Nov 1997 11:25:26 +0100 (MET)
From: Gerard Roudier <groudier@club-internet.fr>
To: Justin Miller <jhm@umr.edu>
cc: linux-scsi@vger.rutgers.edu
In-Reply-To: <199711220206.UAA03575@rocket.cc.umr.edu>
On Fri, 21 Nov 1997, Justin Miller wrote:
> hello again,
>
> I highly recommend against buying Micropolis drives. I have a Stinger
> 4743WS, and I have had nothing but problems with it. I have desperatly
> been trying to return it, the company I bought it from only has a 30 day
> warranty, the the manufacturer warranty applies. Unfortunately
> Micropolis-USA has filed for chapter 11 bankrupcy, and is no longer
> taking responsibility for it's products. Their website has also
Btw, Onsales announced the following: ;-)
On Monday, November 24, ONSALE will auction
vast quantities of Micropolis 9GB & 4GB Hard Drives.
> dissappeared. Does anybody know the drive geometry for this hd, fdisk
> says :
For historical reasons the PC BIOS requires hard disk sectors to be
accessed supplying cylinder, head and sector numbers as input.
In order to optimize media capacity, modern disks donnot use a fixed
number of sectors per _real_ cylinder.
So, the fixed geometry required by PC BIOS never matches the real
geometry of modern hard disks.
The SCSI commands that apply to hard disks only deal with an absolute
sector number starting at number 0.
They are severall constraints about the possible geometry parameters that
can be used for a given HD connected to a given controller, but once a
geometry has been used for partitionning the drive, it is not possible
to change to another one without having to erase some primary data of the
media and losing all the disk data.
> Disk /dev/sdb: 131 heads, 63 sectors, 1017 cylinders
> Units = cylinders of 8253 * 512 bytes
> but according to the scant documentation I have it's supposed to have
> 6565 cylendars.
If 1017*131*63 is less than or equal to the total sector number of your
hard disk, then these values are OK for NCR controllers using the SDMS
bios.
You must be aware of the following when a BIOS is used for a SCSI board:
1 - If you want to be able to boot an O/S from a HD, then the BIOS and
the O/S must use the _same_ geometry parameters for this HD. This
is due to the fact that O/S loaders uses BIOS calls.
2 - All O/Ses you are using on your machine must use the same geometry
for drives they share.
3 - The actual geometry used for SCSI disks is not available from some
BIOS data.
4 - So, it must be deduced from other parameters using some algorithm.
5 - O/Ses have to guess exactly what parameters are used by the BIOS
(and other possible systems).
6 - These algorithms depend on the controller BIOS, and so may depend
on the controller type itself.
Using a biosless controller does not make things a lot simpler.
At least 2,3,4,5 apply in this situation.
All this stuff is a lot messy, but it is the PC history and we must
live with.
BTW, it is not possible to use either an Adaptec or a Buslogic with your
hard disk without having to repartition it, since the actual geometry used
is not in the range allowed for these controllers.
You can found the corresponding algorithms in:
- drivers/scsi/BusLogic.c, function BusLogic_BIOSDiskParameters()
- drivers/scsi/aic7xxx.c, function aic7xxx_biosparam()
- drivers/scsi/scsicam.c function scsicam_bios_param() (NCR using SDMS).
Regards, Gerard.
