dd is an utility which is primarily used for low-level copying of data from storage devices.

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how to use dd to fill drive with 1's

Filling a drive with /dev/urandom seems to be very slow, so I created a file filled with FF: dd if=/dev/zero ibs=1k count=1000 | tr "\000" "\377" >ff.bin I'd like to fill the drive with copies ...
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35 views

dd write vs read performance

I have recently done some performance tests on a new server (using dd) and wonder why read performance is so much worse than write performance? Shouldn't it be another way around? file size was in ...
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32 views

Is this a correct way to back up one big drive to two smaller ones?

I have a pre-fail drive, and while I'm waiting for replacement I am trying to do full back up to two smaller drives. Given that drive is 3TG and ones I have are 1.5 and 2TB, is this a correct way to ...
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1answer
194 views

Partially overwrote /dev/sda, can I recover anything?

I was messing around with my new hard drive, which only contains some personal files, and to check its write speed, I typed: sudo dd if=/dev/zero of=/dev/sda, /dev/sda/ being the new 2 TB connected to ...
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2answers
530 views

Is dd able to overwrite parts of a file?

I have a 1TB big file (disk-image from a damaged drive) and a 1.3MB small file (beginning of a disk-file). Using the contents of the small file, I want to overwrite portions of the big file. That is, ...
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1answer
47 views

How to use pv with dd?

I'm trying to use dd with pv to write an iso to a usb drive. I did: iso="myiso.iso"; dd if="$iso" bs=1M | pv --eta --size $(ls -l "$iso" | awk '{print $5}') --progress --bytes --rate --wait > ...
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2answers
58 views

dd to clone to smaller sdcard

One of my Raspberry Pi's is using a 4GB SDcard for the root/boot filesystem. As seen when mounted on another system: Disk /dev/sdc: 3904 MB, 3904897024 bytes 121 heads, 62 sectors/track, 1016 ...
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92 views

Full DD copy from hdd to hdd

UPDATE: 2 This seems a lot better than before (Thanks to Groxxda for the suggestions): sudo dd if=/dev/sdb bs=128K | pv -s 3000G | sudo dd of=/dev/sdc bs=128K ETA is about 9 hours for 3TB, whereas ...
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3answers
100 views

Why is dd running forever on a 8 GB drive

I have a filesystem handled by ZFS and it's about 8 GB. I tried to zero out the filesystem by running: dd if=/dev/zero of=/EMPTY bs=1M | true rm -f /EMPTY And normally on an ext4 filesystem, it ...
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5answers
628 views

Is it safe to take the drive image of the current working drive?

I have to backup my hard disk. I want to use dd and put the image on an external hdd. Can I do this using dd from the OS that resides on the hdd itself or do I have to boot from another device, for ...
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1answer
49 views

DD with a specific pattern

I was watching this Defcon video and around 4:30 he shows a custom pattern of drive wiping — the drive is filled with a constant text pattern. Whether he is joking or not, is this possible? How would ...
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385 views

1:1 copy with dd

I need to get a copy of an HDD that is a real 1:1, I mean not just the filesystem but also the geometry and the partition table and everything in between. if I'll just use dd if=/dev/sdb ...
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2answers
53 views

`dd` to specific location [closed]

dd is a great tool for copying and conversion. Is there any way by dd (or by any other way), to dump the first few bytes from a file to an unmounted partition? Something like this: dd if=hda2.pbr ...
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59 views

dd: 'bs', 'count' & 'seek'

I've read many guides and forum posts describing how to use dd, but one thing I've noticed is that people always use different values for the 'bs=', 'count=' and 'seek=' switches. Please can someone ...
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1answer
185 views

How to use SSH to make a dd copy of disk A from host B and save on disk B?

I want to make remote backups from disk A at will using SSH from computer B. I want to save the backups to disk B. How can I do this? I've tried using $ ssh hostname@my.ip.add.ress "sudo dd ...
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2answers
67 views

live dd over a mounted read-only root partiton

I'm trying to conceive a firmware update mechanism for a Linux-based embedded system without an additional initrd/initramfs/whatever. From within the running system which has a read-only mounted root ...
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3answers
86 views

Can I overwrite LUKS partition with it's decrypted content?

I have HDD with my data (partial backup of most important data available on other HDD), currently it's formatted as Ext4 over LVM over LUKS. I want to remove LUKS layer, but reformatting and data ...
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2answers
26 views

Backing up a partition

I am pretty new to linux. I mostly started learning after I purchased a couple of Raspberry Pis. I like to make backups of my images as I have often made the mistake of corrupting my data :). ...
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4answers
175 views

dd remove range of bytes

Given this file $ cat hello.txt hello doge world I would like to remove a range of bytes to end up with this $ cat hello.txt heorld I would like to do this with dd if possible. The reason is ...
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2answers
53 views

How to unpack dd file on Windows? [closed]

Is it possible to unpack files created with linux dd tool on Windows? I have tried that tool http://www.chrysocome.net/dd, but it crashes under Windows 7. Any ideas?
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1answer
100 views

dd and rm -r commands

For me, the following commands do exactly the same thing: dd if=/dev/zero of=/dev/sd1 dd if=/dev/null of=/dev/sd1 rm -r /dev/sd1/* meaning, the result of their application is the same. Or least, ...
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1answer
110 views

What does this dd command do exactly?

I have the an embedded device with this SD card: [root@(none) ~]# busybox fdisk -l Disk /dev/mmcblk0: 3965 MB, 3965190144 bytes 4 heads, 16 sectors/track, 121008 cylinders Units = cylinders of 64 * ...
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1answer
114 views

Backup of a ubi file system with dd?

A have a root file system (file system - image containinf folder structure and content) on a flash drive. The flash drive uses UBI as the underlying file system file system - the way the data blocks ...
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1answer
268 views

Writing raw images safely to USB sticks

Trying lots of different linux, on all kinds of hardware I find my self typing commands like this quite often: sudo dd if=xubuntu-13.10-desktop-amd64.iso of=/dev/sdc bs=10240 Needless to say, ...
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4answers
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Why is writing so slow on raw device, and so fast on filesystem (USB key)?

I have a USB key that I am trying to benchmark quick'n'dirty on Linux. I'm testing write bandwith. dd on raw partition I created a partition starting at sector 2048, then did a 4 GB sequential ...
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182 views

how do I do this: dd if=coolstuff.iso of=(ssh kev@mypi )

the card reader on my laptop doesn't want to work. can I use dd (or some other tool) to write an image to a networked disk. I am trying to replace one raspberry pi distro with another. The SD card ...
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2answers
340 views

Create random data with dd and get “partial read warning”. Is the data after the warning now really random?

I create a 1TB file with random data with dd if=/dev/urandom of=file bs=1M count=1000000. Now I check with kill -SIGUSR1 <PID> the progress and get the following: 691581+0 Datensätze ein ...
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3answers
602 views

Read the middle of a large file

I have a 1 TB file. I would like to read from byte 12345678901 to byte 19876543212 and put that on standard output on a machine with 100 MB RAM. I can easily write a perl script that does this. ...
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1answer
76 views

Equivalent of memmove on files: copy a range of bytes to an earlier position

What is an equivalent of memmove on files with the same input and output file? dd works when I move the file contents towards the right, but not if I move the contents left, since there's no handling ...
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1answer
45 views

dd command lost partition

When I used to image my USB, I used the dd command and saved that image to my Hard Disk my USB = sdb1 (4 GB) My partation = sda5 (775 GB free space) dd if=/dev/sdb1 of=/dev/sda5 operation ...
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How to write an alias function to make dd show progress bar?

According to this article, by replacing: $ dd if=/dev/sda of=/dev/sdb [additional options] with: $ pv -tpreb /dev/sda | dd of=/dev/sdb [additional options] one can augment the default dd ...
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dd command: Finding read/write throughput of a flash/SD?

I am running petalinux from sd card. And trying to find data copying rate from Sd card and from QSPI flash that is there on the Xilinx Zynq board. As suggested here , I am doing like this: ...
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1answer
77 views

How use tune2fs in with dd?

In this tutorial is written To regain unique UUIDs, use tune2fs /dev/sdbX -U random on every partition. Ok, but how can I use it with this command? dd if=/dev/sda of=/dev/sdb bs=4096 ...
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1answer
163 views

Why does a disk clone using dd take up more space on the target than the source image?

I'm doing some Android development on Ubuntu 11.10. I'm building a set of SD card and eMMC card Android images using a Bash script. Due to Android's idiosyncrasies, I have several file system images ...
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2answers
155 views

How to backup a running system?

I have a running Linux system, and I'd like to have a full backup of it using dd, which, in my limited knowledge is the only tool every system has. The distro doesn't matter mainly because I should ...
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30 views

For what are disk signatures being used for by GNU/Linux (distributions) / grub?

I am talking about disk signatures in context of the MBR. The area from 441 to 445 bytes. For what does the GNU/Linux kernel, GNU/Linux distributions usually use disk signatures for? I only found ...
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1answer
925 views

Copy MBR and boot partition to a smaller disk

I'm using a 32GB SD card for my raspberry pi. I have successfully transferred the operating system (Archlinux ARM) to a usb harddrive. Which means that I only need the boot partition on the SD card. ...
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1answer
85 views

How to change the disk signature of a raw image?

I am talking about disk signatures in context of the MBR. The area from 440 to 444 bytes. Let's say I got a bootable raw image (bootable in a virtual machine). How can I set the disk signature to a ...
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1answer
363 views

SSH remote backup script

I am trying to backup a remote server to my machine. I am trying something like ssh user@ip "dd if=/dev/sda" | dd of=~/backup.img But that obviously doesn't work. Other variants that don't work. ...
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2answers
580 views

How to clean journals in ext3/ext4 filesystem? [closed]

Some preamble: I'm taking bitwise copy of disk devices (via dd command) from twin hosts (i.e. with the same virtualized hardware layout and software packages, but with different history of usage). To ...
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4answers
2k views

'seek' argument in command dd

Can some explain me what is happening in the following lines? dd if=/dev/urandom bs=4096 seek=7 count=2 of=file_with_holes especially seek part is not clear Man pages says : seek=BLOCKS ...
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2answers
68 views

Debian: Create compressed Harddrive for copy

On my Debian system I have a box with certain configuration settings that I like but I've had to change them continuously. There have been times that I've gotten into a some-what irreversible ...
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362 views

How to restore a DD image file in my primary disk on new debian server

I have a dedicated Debian server at Online.net and I want to change the server by a more powerful (always Debian OS). For that, I have made an image on my old hard disk with this command: dd ...
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1answer
104 views

dd can't see partition but cfdisk and GParted can

I am working with an external HDD and trying to backup a logical partition within an extended partition using dd like this: sudo dd if=/dev/sdb6 of=partition6.dd it returns: dd: opening ...
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1answer
108 views

Partitions same size but different block [closed]

I tried to backup my partition using dd on another disk and I created a partition of the same size. When I finished the copy I had problems mounting the partition since I got bad geometry: block ...
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dd primary partition slow transfer rate

Can someone explain me why if backup ,using dd, a primary partition to a primary partition on other disk the transfer rate (MB/s) is significantly slower compared to the the rate I have if the ...
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146 views

bit-wise complement with dd?

When secure erasing a disk, how can I do a "bit-wise complement" with dd? (or with other UNIX tools?)
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31 views

Backup 'empty' parts of disk drive

I have a USB drive which has around 7MB of 'empty' space at its beginning. The first partition in MBR starts at 8225kB, according to Parted. How can I back up this space using something like dd? ...
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39 views

dd behavior, default writing and partitions

I am confused about the behavior of dd. Say we have some SD card called /dev/foo and this card has partitions /dev/foop0 and /dev/foop1. Using dd, I can set the of argument to /dev/foo and dd won't ...
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2answers
71 views

Backing up a partition: doesn't reflect the status properly

With an intent to check how backing up files/filesystems works, I created 3 part itions sda9, sda10 and sda11. Please see the structure below. (Please ignore sda10 for now as I have already run ...