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UNIX for Advanced & Expert Users
"Phantom" overwrite with dd on sda*?
Post 302921560 by LinQ on Saturday 18th of October 2014 12:41:29 PM
10-18-2014
Yeowtch! Feels like I drew back a stump on that one! I wasn't looking for a dd commandline to clear an HD. I'm simply trying to learn something here --
Peace, friend...
From the OP:
As background, I discovered this behavior quite some time ago while looking for a way to clear the data content from multiple partitions in turn using dd. I found the effects to be quite uniform and harmless in this distro context; which I just reported here.
Then, recently, having seen the post on Stack Exchange which pointed at some formulation of a dd commandline that was reported to have successfully wiped at least one drive using /dev/sda*, I decided to formulate my question for the unix.com communities.
In any event, it seems as though we're just writing to a space in RAM (in this particular context); as calling ls -l on a test case before and after a reboot shows no lasting presence of the created sda* entity. Indeed, a call to top confirms that we're simply draining memory away (used, free, buff, cached):
Before 722040 1349280 88880 500312 (approximate)
>After 1731636 345722 88880 1503648 (approximate)
So, if I might, this begs the next question: What is the significance of the uniform 1.0 GB limit on this action? There's certainly more RAM on-hand in any case.
Still just trying to learn something new here
Thanks again; and have a great day --
Peace, friend...
From the OP:
Quote:
So, the central question is: Why do I always see the same exact records in/out @ 1.0 GB output here, regardless of the target machine/drive? Moreover, what does dd think it's writing to in this case?
Then, recently, having seen the post on Stack Exchange which pointed at some formulation of a dd commandline that was reported to have successfully wiped at least one drive using /dev/sda*, I decided to formulate my question for the unix.com communities.
In any event, it seems as though we're just writing to a space in RAM (in this particular context); as calling ls -l on a test case before and after a reboot shows no lasting presence of the created sda* entity. Indeed, a call to top confirms that we're simply draining memory away (used, free, buff, cached):
Before 722040 1349280 88880 500312 (approximate)
>After 1731636 345722 88880 1503648 (approximate)
So, if I might, this begs the next question: What is the significance of the uniform 1.0 GB limit on this action? There's certainly more RAM on-hand in any case.
Still just trying to learn something new here
Thanks again; and have a great day --
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