[ILUG] New drives getting recognized as device mapper devices

[A. Dreyer]

On Sun, 19 Oct 2008, Walter Faleiro wrote:

> Hi,
> I had two sas disk drives connected to a sunfire X4100 and used half of each
> as /tmp and swap.
> now when I removed them from the original system and connected it to an
> alternate sunfire X4100 they get recognized as below
> 
> Disk /dev/sdb: 146.8 GB, 146810536448 bytes
> 255 heads, 63 sectors/track, 17848 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sdb1               1       17834   143251573+  83  Linux
..
> 
> Disk /dev/dm-0: 146.6 GB, 146695782400 bytes
> 255 heads, 63 sectors/track, 17834 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> 
>      Device Boot      Start         End      Blocks   Id  System
> /dev/dm-0p1               1       17834   143251573+  83  Linux


Hi,

If you want to know more about device-mapper info you might want to save
the data and look at it with a text editor:
	# dd if=/dev/sdb1 of=dm-header bs=1M count=2
	# more dm-header

To clear the device-mapper data from an *empty* partition overwrite the
first 2-4MB with zeros:
	# dd if=/dev/zero of=/dev/sdb1 bs=1M count=2


Regards,
Achim


-- 
Achim Dreyer                || http://www.adreyer.com/
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