[clug] OT: newbie RAID question

[Michael Cohen]

Hi Carlo,

On Fri, Jun 4, 2010 at 10:17 AM, Carlo Hamalainen
<carlo.hamalainen at gmail.com> wrote:
> The drive in question has confidential information on it. I've been
> told that one can't reconstruct the array from a single drive, which
> is fine, but if someone runs a low level scan of the drive, won't they
> see snippets of data?

Yes they will. In a 3 disk RAID5 one disk is used for parity and two
for data. The parity is usually rotated through the disks. They will
see half the data for the blocks that dont have parity. Even with
parity if one of the other disks is all 0 they will see the data
(because parity of one block with data and one block with 0 is the
data again - simple xor operation).

Usually if you are a big enough organization you can just tell them
they can not have the disk back. Im not sure for smaller organization
you would have that negotiating power.

Michael.