[NTLUG:Discuss] How to move data from one drive to another

[Bryan J. Smith]

On Thu, 2005-08-04 at 22:23 -0500, Stuart Johnston wrote:
> If you are using dd, you never mount the drives.
> Why would the file system matter?

Ooops, sorry, getting ahead of myself.  Yes, you are correct.
If you're just using dd, then it doesn't matter.

> I've probably copied drives with dd 3 or 4 different times.  Never were 
> the drives the same size or brand.  Most recently it was a 5-year-old, 
> 20G, WD drive onto a new Hitachi 80G.  Is it possible that I just got 
> lucky and these otherwise completely different drives have the same 
> geometry?

Most BIOSes use LBA (Logical Block Addressing), so they use a 8MiB
cylinder using 255 heads and 63 sectors/cylinder.  In those cases, you
can typically get away with dd.

Of course, newer ATA-6/48-bit (>133GB/128GiB) addressing allows for
greater geometries including, logically, >255 heads and >63 sectors.

> Seems unlikely to me but then I've never really understood 
> the complexities of modern drive geometry (LBA modes, BIOS vs. OS, 
> physical/logical).

I recently covered low-level Windows and UNIX interoperability at the
St. Louis UNIX User's Group (SLUUG).  It was last second, but it was a
quick intro.

See slides 5-8 in part I:  
  http://geocities.com/thebs413/SLUUG_LowLevelInterop_Part1.pdf  

And slides 4-5 in Part II:  
  http://geocities.com/thebs413/SLUUG_LowLevelInterop_Part2.pdf  
  
For discussions on basic geometry as well as dual-booting issues.

There is also a Part III:  
  http://geocities.com/thebs413/SLUUG_LowLevelInterop_Part3.pdf  

Which talks about the inherent design limitations of NTFS itself, as
well as the new Logical Disk Manager (LDM) disk label (partition table)
format.
  

-- 
Bryan J. Smith     b.j.smith at ieee.org     http://thebs413.blogspot.com
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