|
|
Sponsored Content
Top Forums
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 --
|
|
9 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
Hi Friends,
Can any of you explain me about the below line of code?
mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'`
Im not able to understand, what exactly it is doing :confused:
Any help would be useful for me.
Lokesha (4 Replies)
Discussion started by: Lokesha
4 Replies
2. UNIX for Advanced & Expert Users
Hi everyone:
I have built a tcl script, this script communicate with an ADA program trough a socket, sending binary data, the sender proc is this one:
The code where im sending info is here:
proc p_send_data { DATA } {
global connection
puts "Sending trough $connection..."
#... (2 Replies)
Discussion started by: trutoman
2 Replies
3. Shell Programming and Scripting
hi All,
cat file_name | awk /^~/'{print $1","$2","$3","$4}' | sed -e 's/~//g'
Can this be done by using sed or awk alone (4 Replies)
Discussion started by: harshakusam
4 Replies
4. Shell Programming and Scripting
Hi,
I have line in input file as below:
3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL
My expected output for line in the file must be :
"1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL"
Can someone... (7 Replies)
Discussion started by: shis100
7 Replies
5. Shell Programming and Scripting
logs:
"/home/abc/public_html/index.php"
"/home/abc/public_html/index.php"
"/home/xyz/public_html/index.php"
"/home/xyz/public_html/index.php"
"/home/xyz/public_html/index.php"
how to use "cut" or "awk" or "sed" to get the following result:
abc
abc
xyz
xyz
xyz (8 Replies)
Discussion started by: timmywong
8 Replies
6. Solaris
The system don't boot.
on the screen appears following:
press enter to maintenance (or type CTRL-D to continue)...I checked with format command.
... the slices "0-root","1-swap","2-backup" exist.
...the slises "3-var","6-usr" -unassigned. :( (16 Replies)
Discussion started by: wolfgang
16 Replies
7. UNIX for Dummies Questions & Answers
How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing “To” e-mail address
and column 3 contains “cc” e-mail address to include with same email.
Sample input file, email.txt
Below is an sample code where... (2 Replies)
Discussion started by: asjaiswal
2 Replies
8. Shell Programming and Scripting
Hello.
System : opensuse leap 42.3
I have a bash script that build a text file.
I would like the last command doing :
print_cmd -o page-left=43 -o page-right=22 -o page-top=28 -o page-bottom=43 -o font=LatinModernMono12:regular:9 some_file.txt
where :
print_cmd ::= some printing... (1 Reply)
Discussion started by: jcdole
1 Replies
9. AIX
Hi 2 all,
i have had AIX 7.2
:/# /usr/IBMAHS/bin/apachectl -v
Server version: Apache/2.4.12 (Unix)
Server built: May 25 2015 04:58:27
:/#:/# /usr/IBMAHS/bin/apachectl -M
Loaded Modules:
core_module (static)
so_module (static)
http_module (static)
mpm_worker_module (static)
... (3 Replies)
Discussion started by: penchev
3 Replies
LEARN ABOUT CENTOS
ocf_pacemaker_healthsmart
OCF_PACEMAKER_HEALTH(7) Pacemaker Configuration OCF_PACEMAKER_HEALTH(7) NAME
ocf_pacemaker_HealthSMART - SMART health status SYNOPSIS
OCF_RESKEY_state=string OCF_RESKEY_drives=string OCF_RESKEY_devices=string OCF_RESKEY_temp_lower_limit=string OCF_RESKEY_temp_upper_limit=string OCF_RESKEY_temp_warning=string HealthSMART [start | stop | monitor | meta-data | validate-all] DESCRIPTION
Systhem health agent that checks the S.M.A.R.T. status of the given drives and updates the #health-smart attribute. SUPPORTED PARAMETERS
OCF_RESKEY_state = string [/HealthSMART-{OCF_RESOURCE_INSTANCE}.state] State file Location to store the resource state in. OCF_RESKEY_drives = string [/dev/sda] Drives to check The drive(s) to check as a SPACE separated list. Enter the full path to the device, e.g. "/dev/sda". OCF_RESKEY_devices = string Device types The device type(s) to assume for the drive(s) being tested as a SPACE separated list. OCF_RESKEY_temp_lower_limit = string [0] Lower limit for the red smart attribute Lower limit of the temperature in deg C of the drive(s). Below this limit the status will be red. OCF_RESKEY_temp_upper_limit = string [60] Upper limit for red smart attribute Upper limit of the temperature if deg C of the drives(s). If the drive reports a temperature higher than this value the status of #health-smart will be red. OCF_RESKEY_temp_warning = string [5] Deg C below/above the upper limits for yellow smart attribute Number of deg C below/above the upper/lower temp limits at which point the status of #health-smart will change to yellow. AUTHOR
Andrew Beekhof <andrew@beekhof.net> Author. Pacemaker Configuration 06/10/2014 OCF_PACEMAKER_HEALTH(7)