HDD , HPA , and DCO ?

[sam111]

What type of data is held in the HPA , and DCO typically (if any)?
And when would you every have to use this other then to make a drive appear to have a different physical size/geometry?

What is good linux software that would allow you to create/read/write to HPA , DCO sectors of a Harddrive?

[oz]

Wikipedia has a couple of articles that cover these areas on a hard disk along with some tools for working with them:

Device configuration overlay - Wikipedia, the free encyclopedia

Host protected area - Wikipedia, the free encyclopedia

[sam111]

Ya , I looked thru those.
But I was curious it seems from what I read it is just to make a drive appear with a smaller size/geometry to the bios and OS.

I was wondering if anybody has used these areas for anything (i.e forensics ...) out their.
By default it seems HPA , DCO is off on this HDD of mine.
Also wondering if any linux based or windows based machine use HPA , or DCO. Or is it by default off on HDD and you must enable it before using it.

Because it would seem that HPA , DCO would always be disabled by default and if it was enabled you would probably know about it since you would have to first enable it? Making these areas not so secret any way

[connollyg]

Most RAID systems store config data on the disks in a RAIDset, things like, which disks and what order they are accessed in. These areas are not normally visible to the systems using the RAIDset and are maintained by the RAID controller.

[sam111]

Ok well other then raid. Is their any purpose for those protection areas.
Since I don't use raid I have check all my HDD with hdparm and they all suggest that I don't really have those areas enabled.

Does any HDD come with these areas enabled by default and being used for some purpose other then raid?