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Old 12-01-2013, 03:59 AM   #1
Xeratul
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Create a virtual harddisk using dd ?


Hi,

Usually I created my harddisk using the qemu-img.
Code:
qemu-img create virtdisc.img 1G
In the past, I did simply use :
dd
cfdisk
and mkfs.vfat.

However I absolutely cannot find using google on the web.
I really think that I made it but how...
Impossible to find back


Would you know how to create a virtual image of free
formated harddisk of 1gb as the above alternative technique?

Thank you in advance
 
Old 12-01-2013, 05:15 AM   #2
mjolnir
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http://www.adayinthelifeof.nl/2011/1...l-disk-images/

This guy uses fdisk and "dd".

"There are multiple ways to do this, but one of the easiest methods is to use either “dd” or “bximage”. The latter one is a tool from the Bochs Emulator that can create disks."

"Another way is to use the “dd” utility that comes on most unix/linux systems:

dd if=/dev/zero of=hdd.img bs=1024 count=10240"

"Partition the image through fdisk
Now that we have a completely blank file (or virtual disk), we need to partition it just like any other disk. The “fdisk” utility it the way to go here, and there is nothing different between creating partitions on a virtual disk than it is on a physical one.

fdisk hdd.img
I’ve added a bunch of partitions (again: I’m testing my OS here, so it needs to be able to handle stuff like extended partitions etc). Just make sure you set the correct settings for your cylinders, heads and sectors-per-track in the fdisk menu. They are located in the “Expert menu” through “x”. I’ve added a big 5MB partition for Linux, a small 2MB partition for dos/fat16, another 1.5MB for linux, and a-little-bit-less-than-1MB partition for Linux, but I’ve put the last one inside an extended partition:

# fdisk -l -u hdd.img -C 20 -H 16 -S 63

Disk hdd1.img: 0 MB, 0 bytes
16 heads, 63 sectors/track, 20 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x839d4362

Device Boot Start End Blocks Id System
hdd.img1 63 10079 5008+ 83 Linux
hdd.img2 10080 15119 2520 6 FAT16
hdd.img3 15120 18143 1512 83 Linux
hdd.img4 18144 20159 1008 5 Extended
hdd.img5 18207 20159 976+ 83 Linux"

"Format the partitions
At this point you are able to format the partitions. Again, just like any physical partition.

# mkfs.ext2 /dev/loop1
# mkdosfs /dev/loop2
# mkfs.ext2 /dev/loop3
# mkfs.ext2 /dev/loop5"

He's making loop-back devices but you can adapt it too your needs.

Last edited by mjolnir; 12-01-2013 at 05:16 AM.
 
Old 12-02-2013, 07:05 PM   #3
jefro
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Some of the pen drive pages offer ways but I think above has covered the basics.


Qemu-img can also create format specific virtual hard drives, a qcow2 or soon to be qcow3 has some advantages. An unfilled qcow2 is about 2 seconds of time where the dd has to fill the entire area bit by bit.
 
Old 12-03-2013, 06:47 PM   #4
Xeratul
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Quote:
Originally Posted by jefro View Post
Some of the pen drive pages offer ways but I think above has covered the basics.


Qemu-img can also create format specific virtual hard drives, a qcow2 or soon to be qcow3 has some advantages. An unfilled qcow2 is about 2 seconds of time where the dd has to fill the entire area bit by bit.
Qemu-img, bximage, ... but still, with dd is must be possible. I have written down somewhere how (maybe).
 
Old 12-04-2013, 07:23 PM   #5
jefro
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I think this is correctly reported by mjolnir,


dd if=/dev/zero of=hdd.img bs=1024 count=10240"


If not see this too. http://lnx.cx/docs/vdg/output/Virtua...pts-Running-dd
 
Old 12-05-2013, 07:30 AM   #6
mjolnir
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@jefro Nice link.
 
  


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