Different translations of HDD geometry :-(

[Geir Holmavatn]

Hi,

I'm responsible of maintaining quite a pile of computers and to save time I
have stored disk images of a fresh windows install with all appropriate
applications, drivers and settings. This makes it quick to restore a
computer to its 'original' state.

However apparently is disk geometry translated differently from brand to
brand. Compaq hdds cannot be sector by sector copied by another brand, the
software reports Invalif partition table or does not find any os at all.
The same problem is found with Dell hdds. This is probably due to different
algoritms in detetecting / deciding a drive's geometry (sectors/tracks, LBA
etc...) at the BIOS level.

I want (or shall we say *need*) to have *one* desktop PC which can be
tweaked to set the hdd geometry to match any of the original computers, so I
don't need to keep one computer of each brand/model just for the
mirroring.... Can this be done? Does it exist software which does this...?

Thanks a lot for comments and advice

best regards

Geir

 

[Folkert Rienstra]

There is only one geometry for drives over 8 GB.

 

[Geir Holmavatn]

There is only one geometry for drives over 8 GB.

So what can be read differently from different machines then? Only Compaq
Deskpro EN can read its own hdds, same with Dell Optiplex 240 I get either
invalid partition table or unknown operating system when trying to read
disks from these machines on another computer.

I was sure it was the geometry assumption logic...

Any other clues?

regards

Geir

 

[Rod Speed]

So what can be read differently from different machines then? Only
Compaq Deskpro EN can read its own hdds, same with Dell Optiplex
240 I get either invalid partition table or unknown operating system
when trying to read disks from these machines on another computer.

I was sure it was the geometry assumption logic...

Any other clues?

Some systems do have maintenance partitions etc.

Maybe its not the geometry so much as how the initial boot phase works etc.

 

[Folkert Rienstra]

So what can be read differently from different machines then?

Only Compaq Deskpro EN can read its own hdds, same with Dell Optiplex 240

Sounds like they are not booting the same way as 'standard' computers do.
All a 'standard' computer does is read the first sector and execute the
code in it, which code then takes over.

If a drive doesn't boot on another computer then either the orignal computer
accesses the drive without the bootsector code or the bootsector code has some
(hardware)system dependent code in it that forks differently depending of system.
It's also possible that the bioses of the original computers use the "Address Off-
set Reserved Area Boot Method" so that a special bootsector in a hidden area is
started that can make sense of the partitions where the standard bootcode can not.

I get either invalid partition table or unknown operating system
when trying to read disks from these machines on another computer.

You will have to find out where those error messages are generated from.

I was sure it was the geometry assumption logic...

Doesn't make sense.

 

[powerstation]

Some systems do have maintenance partitions etc.

Maybe its not the geometry so much as how the initial boot phase works
etc.

I have a compaq EN SFF and had the exact same problem when I cloned the hdd
in another computer, back in the Compaq partion magic protested at the clone
as different geometry and refused to read it, but it worked fine in the
machine it was cloned in. The only way I could clone this hdd was to do it
in the Compaq machine which was a pain because it only had a special
connector on the secondary for the slim CD rom.

 

[Arno Wagner]

Hi,

I'm responsible of maintaining quite a pile of computers and to save time I
have stored disk images of a fresh windows install with all appropriate
applications, drivers and settings. This makes it quick to restore a
computer to its 'original' state.

However apparently is disk geometry translated differently from brand to
brand. Compaq hdds cannot be sector by sector copied by another brand, the
software reports Invalif partition table or does not find any os at all.
The same problem is found with Dell hdds. This is probably due to different
algoritms in detetecting / deciding a drive's geometry (sectors/tracks, LBA
etc...) at the BIOS level.

I want (or shall we say *need*) to have *one* desktop PC which can be
tweaked to set the hdd geometry to match any of the original computers, so I
don't need to keep one computer of each brand/model just for the
mirroring.... Can this be done? Does it exist software which does this...?

Hmmm. Maybe this is an entirely different issue. Maybe the boot
manager/boot code you use is broken or old and needs a specific
disk geometry to work? The "invalid partition table" is not something
the BIOS can do. BIOS does not know about or understands partition
tables. That is the job of the boot code loaded from the MBR on the
disk.

One cheap thing you could try is booting everythign with GNU Grub.
Grub does boot allmost anything (XP with chainloader) and does LBA
to find partitions.

One other possibility is that you use broken/very old software to
partition your drives. I am not sure, but if you partition for
a apecific C/H/S value, some sectors could be skipped and a
direct translation does not work anymore. This only happens
if the partitioning software itself is not LBA capable and does
translation from one C/H/S value to another.

Arno

 

[Eric Gisin]

Hmmm. Maybe this is an entirely different issue. Maybe the boot
manager/boot code you use is broken or old and needs a specific
disk geometry to work? The "invalid partition table" is not something
the BIOS can do. BIOS does not know about or understands partition
tables. That is the job of the boot code loaded from the MBR on the
disk.

"Invalid Partition Table" comes from the standard MBR.
Of course you would not know that, as you are blithering Linux Freak.
It means than none or multiple partitions are marked active.