Re: Matching file to a physical medium

[Johnny Billquist <bqt%softjar.se@localhost>]

On 10/14/10 15:49, Sad Clouds wrote:
> Hi, does anyone know if there is a way to match a file to a particular
> physical medium, such as a disk.
>
> With the help of stat(2) I can get st_dev for this file, but st_dev is
> unique for each file system, even if those file systems reside on the
> same physical disk. What I need is something that can uniquely identify
> a physical disk.
>
> Any ideas?

Afraid I don't know of any good way to do this.
The information is encoded in the st_dev value, but it is not standardized.
The major number will tell you what type of device it is, but the minor 
number will tell you both which specific disk, and which partition of 
that disk. So it is split into two parts, and you'd like to look at just 
one part of that.
However, the split between unit and partition in the minor number 
depends on the actual type of disk we talk about.
Some have minor as (unit * 8) + partition, while others have (unit * 
16)+partition, and some have an even more odd scheme. See /dev/MAKEDEV 
for some details. Or else the various device drivers.

        Johnny