[nSLUG] Hard Disk question

Dop Ganger nslug at fop.ns.ca
Fri Mar 7 10:46:37 AST 2008

On Fri, 7 Mar 2008, J. Paul Bissonnette wrote:

> jpb at maple:~$ sudo fdisk -l /dev/hdd
> Disk /dev/hdd: 80.0 GB, 80026361856 bytes
> 255 heads, 63 sectors/track, 9729 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Disk identifier: 0x00014e08
>   Device Boot      Start         End      Blocks   Id  System
> /dev/hdd1               1        9729    78148161   83  Linux

That certainly looks reasonable; 9729 cylinders, and /dev/hdd1 starts at 1
and ends at 9729. Try:

mke2fs -b 4096 -N 1024 -m 0 /dev/hdd1

This will format /dev/hdd1 as ext2fs with options to use as little space
as possible for filesystem overhead (and as a result will be fairly
unusable - only 1024 inodes will not get you too far these days). Mount it
and if the partition table is correct you should see somewhere between 70
and 80 gig free.

> The disk was partitioned with only one partition, it is being used as a
> temporary storage  - scratch pad. Anything important that was on that
> disk is stored to removable media. When it is deleted I want it cleaned.
> rm doesn't do much of a job of removing files, they are recoverable.

If you're concerned about someone picking off files, don't fill the 
partition, fill the drive:

dd if=/dev/zero of=/dev/hdd bs=64M

Recreate and reformat the partition and you're good to go. Filling up the 
partition itself doesn't work because you can still have data hiding in 
the directory structure, packed tails, etc.

In theory someone could still use a scanning tunnelling microscope to pull 
data off but it's usually not a concern in practice.

Cheers... Dop.

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