29Oct/14

ZFS variables list & info – zfs arc – and – sysctl zfs variables – and links to zfs source code

2014-10-29Linuxkossboss

NOTE: Material below is copied from http://www.krausam.de/?p=70. Go to that site for most up to date info. Lots of useful ZFS information comes from this command: echo ::arc | mdb -k Also there are otherRead More…

22Oct/14

JOBS & PROCESS CONTROL – MULTIPLE COMMANDS WITH IN A NOHUP

2014-10-22Linuxkossboss

MULTIPLE COMMANDS WITH IN A NOHUP ################################### Nohup is useful to run things in the background tied away from the session shell (putty or teraterm or etc.). So that if you closeRead More…

10Oct/14

SSL CERTIFICATE CHECKS FAIL ALL THE TIME (git & wget & etc…)

2014-10-10Linux, Linux and Windowskossboss

SSL CERTIFICATE CHECKS FAIL ALL THE TIME (git & wget & etc…) ################################################### If your trying to download something from github with “git clone” or wget from an https site – andRead More…

10Oct/14

spf13 – vim keys – my own cheatsheet

2014-10-10Linux, Linux and Windowskossboss

spf13 – vim keys – my own cheatsheet ##################################### NOTE: sections are seperated out with the yellow highlights and underlines Lots of these work without spf13 plugins. I assume basic knowledge ofRead More…

09Oct/14

Installing SPF13 for VIM & fixing SSL certificate errors – linux/cygwin

2014-10-09Linux, Linux and Windowskossboss

Installing SPF13 for VIM, when getting SSL certificate errors What is spf13? Its the best vim plugins install available online in my opinion http://vim.spf13.com/ To checkout my spf13 vim cheatsheet: www.infotinks.com/spf13c IfRead More…

07Oct/14

BTRFS – Recovery Mount – The ultimate mount command

2014-10-07Linuxkossboss

If this doesn’t mount your volume, pray to justice you have a backup. (Wait you don’t have a backup of all your precious data? Terrible mistake… Make one now)

mount /dev/sda1 /data -t btrfs -o nospace_cache,clear_cache,enospc_debug,nodatacow

1	mount /dev/sda1 /data -t btrfs -o nospace_cache,clear_cache,enospc_debug,nodatacow

NOTE: ofRead More…

06Oct/14

ddestroy – Write Zeros To Random Locations Across Drive

2014-10-06Linuxkossboss

Read the source code and the comments to understand what this does.

#!/bin/bash
# ---
# this will write 0s across a drive at random locations (using dd)
# you specify the details in the variables location
# ---
# fill out these variables & copy paste script & it will not hurt (it will not do the writes)
# For security purposes:L you will see the dd commands output (but they will not run)
# To run them just select and copy the dd commands, and paste them back into the shell to run them
# ---
# You could also run the script and save it to a file
# first edit ddestroy.sh to have the correct variables, then save and exit, and run the code like this:
# $ ./ddestroy.sh > ddcommands
# this will save all of the dd commands (and comments of the output) into the ddcommands file
# now we just run the ddcommands file to execute those commands
# since the output ddcommands, will not have +x bit, you can just run it with the bash "source" commands
# $ source ddcommnds
(#####################
### SET VARIABLES ###
### ALL IN MiBs #####
### Megabytes #######
#####################
DISK=sda
START_LOCATION=0
MAX_SIZE_OF_A_WRITE=1000
MIN_NUM_OF_WRITES_TO_DISK=24
##  example:
##  DISK=sda
##  START_LOCATION=0
##  MAX_SIZE_OF_A_WRITE=1000
##  MIN_NUM_OF_WRITES_TO_DISK=12
##  This will write to disk sda, from the beginning due to the 0 START_LOCATION
##  1 gig writes due to MAX_SIZE_OF_A_WRITE (max, but they will vary in size)
##  at about 12 locations due to MIN_NUM_OF_WRITES_TO_DISK 
##  but since thats random too, it might be more locations)
######################
### start of code ####
######################
SIZE=`cat /sys/block/$DISK/size`
echo "# Size of disk '$DISK' is $SIZE sectors"
SIZE_MB=`echo $SIZE | awk '{printf("%d",$1/2/1024)}'`
echo "# Size of disk '$DISK' is $SIZE_MB megabytes"
### INPUT TO AWK: start location, write size max (but they all are random), max size of drive - all in MB, name of disk, min_number_of_writes_to_disk
echo "$START_LOCATION $MAX_SIZE_OF_A_WRITE $SIZE_MB $DISK $MIN_NUM_OF_WRITES_TO_DISK" | awk '{
srand();
start=int($1);
wrmax=int($2);
ms=int($3);
name_of_drive=$4;
cu=start;
range1=ms-start;
min_number_of_writes=$5;
random_division=min_number_of_writes/2;
print "### WRITING AT RANDOM LOCATIONS (all units in MiB) ###"
print "# - start_location: " cu;
print "# - size_of_disk: " ms;
print "# - max_random_size_write: " wrmax;
print "# - min_number_of_total_writes: " min_number_of_writes;
print "# - drive: " name_of_drive;
i=1;
while (cu<ms)
{
wr=int(wrmax*rand())+1; # random write amount
printf("# write number : %d - current: %d", i, cu);
ri=int(rand()*(range1/random_division));
printf(", skipping: %d, writing: %d\n", ri, wr);
printf("dd if=/dev/zero of=/dev/%s bs=1M skip=%d count=%d\n", name_of_drive, cu, wr);
cu=cu+ri+wr;
i=i+1;
}}')

#!/bin/bash

# ---

# this will write 0s across a drive at random locations (using dd)

# you specify the details in the variables location

# ---

# fill out these variables & copy paste script & it will not hurt (it will not do the writes)

# For security purposes:L you will see the dd commands output (but they will not run)

# To run them just select and copy the dd commands, and paste them back into the shell to run them

# ---

# You could also run the script and save it to a file

# first edit ddestroy.sh to have the correct variables, then save and exit, and run the code like this:

# $ ./ddestroy.sh > ddcommands

# this will save all of the dd commands (and comments of the output) into the ddcommands file

# now we just run the ddcommands file to execute those commands

# since the output ddcommands, will not have +x bit, you can just run it with the bash "source" commands

# $ source ddcommnds

(#####################

### SET VARIABLES ###

### ALL IN MiBs #####

### Megabytes #######

#####################

DISK=sda

START_LOCATION=0

MAX_SIZE_OF_A_WRITE=1000

MIN_NUM_OF_WRITES_TO_DISK=24

## example:

## DISK=sda

## START_LOCATION=0

## MAX_SIZE_OF_A_WRITE=1000

## MIN_NUM_OF_WRITES_TO_DISK=12

## This will write to disk sda, from the beginning due to the 0 START_LOCATION

## 1 gig writes due to MAX_SIZE_OF_A_WRITE (max, but they will vary in size)

## at about 12 locations due to MIN_NUM_OF_WRITES_TO_DISK

## but since thats random too, it might be more locations)

######################

### start of code ####

######################

SIZE=`cat /sys/block/$DISK/size`

echo "# Size of disk '$DISK' is $SIZE sectors"

SIZE_MB=`echo $SIZE | awk '{printf("%d",$1/2/1024)}'`

echo "# Size of disk '$DISK' is $SIZE_MB megabytes"

### INPUT TO AWK: start location, write size max (but they all are random), max size of drive - all in MB, name of disk, min_number_of_writes_to_disk

echo "$START_LOCATION $MAX_SIZE_OF_A_WRITE $SIZE_MB $DISK $MIN_NUM_OF_WRITES_TO_DISK" | awk '{

srand();

start=int($1);

wrmax=int($2);

ms=int($3);

name_of_drive=$4;

cu=start;

range1=ms-start;

min_number_of_writes=$5;

random_division=min_number_of_writes/2;

print "### WRITING AT RANDOM LOCATIONS (all units in MiB) ###"

print "# - start_location: " cu;

print "# - size_of_disk: " ms;

print "# - max_random_size_write: " wrmax;

print "# - min_number_of_total_writes: " min_number_of_writes;

print "# - drive: " name_of_drive;

i=1;

while (cu<ms)

{

wr=int(wrmax*rand())+1; # random write amount

printf("# write number : %d - current: %d", i, cu);

ri=int(rand()*(range1/random_division));

printf(", skipping: %d, writing: %d\n", ri, wr);

printf("dd if=/dev/zero of=/dev/%s bs=1M skip=%d count=%d\n", name_of_drive, cu, wr);

cu=cu+ri+wr;

i=i+1;

}}')

Here is an example of the output of the above script (run with above variables, in your case youRead More…

M	T	W	T	F	S	S
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6	7	8	9	10	11	12
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20	21	22	23	24	25	26
27	28	29	30	31

infotinks

My Notes, Articles & Guides for Linux, Windows and Networking.

Monthly Archives: October 2014

ZFS variables list & info – zfs arc – and – sysctl zfs variables – and links to zfs source code

JOBS & PROCESS CONTROL – MULTIPLE COMMANDS WITH IN A NOHUP

SSL CERTIFICATE CHECKS FAIL ALL THE TIME (git & wget & etc…)

spf13 – vim keys – my own cheatsheet

Installing SPF13 for VIM & fixing SSL certificate errors – linux/cygwin

BTRFS – Recovery Mount – The ultimate mount command

ddestroy – Write Zeros To Random Locations Across Drive