Questions tagged [dd]

dd is a traditional utility for binary data copies

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1answer
1k views

How to clone an entire disk to a larger disk and then offload?

What I have done is clone a small 32GB flash module that had three partitions. I happened to have a 32GB USB lying around, so I thought it might just work; it did not. It seems 32GB from Toshiba is a ...
4
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1answer
38 views

Looking for a way to backup/mirror a drive by swapping

I want to duplicate a drive. I am unable to hook up both the old and new drive at the same time (the old powerbrick died; so I have one powerbrick to swap between two drives). In years and years ...
1
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1answer
380 views

BASH dd problem

i am trying to learn bash and now im trying to do a script for burning isos. I made the number "4" command to make sure the variables were right. the message i get when i complete my program and ...
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2answers
921 views

Can I use dd to move my system to another partition?

Currently, my whole system is located at the end of my hdd. I'd like to move that data to the beginning and still have booting and other details working. dd seems to do exactly what I want (to copy ...
2
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0answers
898 views

how to copy a piece of a text file byte-by-byte to another text file? dd, head, or?

I need to grab the first lines of a long text file for some bugfixing on a smaller file (a Python script does not digest the large text file as intended). However, for the bugfixing to make any sense, ...
0
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3answers
576 views

dd show 'raw' progress while piping output

I am attempting to perform a specific dd operation and appending 'raw' data of the transfer to a log file which will be polled by something else, to provide a live view of the transfer on another ...
0
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1answer
176 views

Restore a disk from a snapshot in XEN 4.6

I created a snapshot with lvcreate -n snap01.vm01 -L 5G -s vg0/vm01.eclabs.de now I did some stuff on my disk i don't want to keep and want to revert it to the snapshot point. How do I restore the ...
5
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2answers
317 views

confused about dd write speed and VFS page cache

After reading some articles on the Linux VFS page cache and the tunable parameters like dirty_ratio i was under the impression that page cache would operate as both read and write caching layer. But ...
1
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1answer
361 views

LVM devices not showing in initrd but working on boot [duplicate]

I am currently working on a custom initrd based on the CentOS 6.7 (2.6) kernel with the following modules loaded. The initrd is designed to backup files off a old RHEL system into memory, unmount the ...
2
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0answers
269 views

IOSTAT report doesn't match with DD benchmark

I am running a DD benchmark but the obtained results are not matching with the IOSTAT values. This is the DD sample: $ sudo dd bs=4096 count=690 if=/dev/zero of=/mnt/tmp/test oflag=dsync 690+0 ...
1
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1answer
85 views

Wipe files from an external hard drive but not empty space

I'm using the following command to wipe an external drive. sudo shred -v -z -n 1 /dev/sdb Is it possible to wipe an external drive of the files and not empty space? So it would overwrite where there ...
0
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1answer
181 views

GDiskDump or DD to show partition names? [duplicate]

I have partition names like Data-HD, Yhteinen and W10. I do have lots of other partitions, but I want a little more assurance I am copying a right partition to a correct destination. I am quite ...
4
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1answer
4k views

Taking and restoring an image of partition with dd

I created a new partition on my server /dev/sda4 with a filesystem based on ext3. I mounted the new partition /dev/sda4 on /mnt/sda4/ and created an image with dd of the partition /dev/sda3. sda3 is ...
5
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2answers
1k views

How large is the img that dd creates?

This is the first time I use the dd command. I execute: dd if=/dev/sdb2 of=/mnt/sdc1/Hdd1.img bs=512 conv=noerror,sync Where the sdb is the destroyed hdd (size: 500 GB). I copying the partition sdb2 ...
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0answers
30 views

Is it feasible to fill a ntfs partition/device pre install with zeroess?

In my question about copying with dd one of the commentors pointed out the method of filling the unused space with 0s. Is there a way for a dd of a 80 GB hard drive to be minimal in size? Now after ...
2
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1answer
165 views

Is there a way for a dd of a 80 GB hard drive to be minimal in size?

For backup reasons I need to use dd to copy a whole hard drive (including MBR, partitions,...). The hard drive is 80 GB in size where only 1.8 GB are used. The command I'm using is the following: dd ...
0
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1answer
35 views

Used dd on a pen drive (wrote Arch to it with Rufus) and now it's invisible

I ran dd if=/dev/zero of=/dev/sdc count=2048 on the pen drive. I can see the pen drive in the lsusb output, and dmesg says that it is 8 GB in size, but when I use, say, cfdisk, it says that there is ...
3
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3answers
8k views

MBR size is 440 bytes or 512 bytes

I remembered reading one question how would you back up the MBR of a disk. Two of the choices are dd if=/dev/sda of=/dev/sdb bs=512 count=1 dd if=/dev/sda of=/dev/sdb bs=440 count=1 and the ...
1
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2answers
3k views

dd count default

What is the count default in dd command if not specified ? dd if=/dev/mem bs=1k skip=768 instead of full form like dd if=/dev/mem bs=1k skip=768 count=50 I did not find an answer with Google.
1
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1answer
637 views

I/O Failure when overwriting entire disk

I'm trying to write random data over a partition on my local hard disk. I'm booted into a recovery live CD (Clonezilla) and have tried the following: $ dd if=/dev/urandom bs=1024 count=4 | base64 | \ ...
1
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1answer
514 views

Parallelize openssl as input to dd

I am using @tremby's great idea to fill a disk with random data. This involves piping openssl, which is encrypting a lot of zeros, to dd (bs=4M). I'm maxing out the single core on which this is ...
2
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1answer
1k views

Transfer content of LVM block device ensuring consistency - LVM snapshot?

I need to create off-site full backups of an LVM block device. Thinking the old dd over SSH method. To ensure I have a consistent backup, should I create an LVM snapshot first? So new changed blocks ...
4
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2answers
2k views

how to deallocate /dev/ram0

I have allocated /dev/ram0: dd if=/dev/zero of=/dev/ram0 bs=1M count=1024 Now I have 1Gb sitting in memory. How do I free up the allocated space ?
2
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2answers
706 views

How can I manipulate a partition table file without fdisk checking the validity of it?

I'm creating an image in memory (/tmp is a tmpfs): $ dd if=/dev/zero of=/tmp/sdcard.img bs=512 count=3147775 It's supposed to hold a partition table and the first 3 partitions of a device $ losetup ...
1
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1answer
4k views

Using dd command to download mtd block

How to use dd command to download mtd block from embedded Linux-based device? # cat /proc/mtd dev: size erasesize name ... mtd3: 003a0000 00010000 "DRTI2" I need download mtd3 block, so dd if=...
17
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2answers
1k views

Why do these duplicated SD cards have different sha1sums for their content?

I have a bunch of Class 10 UHS-1 SDHC SD cards from different manufacturers. They are all partitioned as follows $ sudo fdisk -l /dev/sdj Disk /dev/sdj: 14.9 GiB, 15931539456 bytes, 31116288 sectors ...
4
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2answers
516 views

Is `dd` really necessary to clone a disk? [duplicate]

Almost any tutorial will tell you that to clone a disk on the command line (say, to clone /dev/sda to /dev/sdb) you can use: dd if=/dev/sda of=/dev/sdb ...and some block size options... This reads ...
1
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1answer
1k views

dd, cat & openssl: block size & buffer size

Here it says that when using dd through dm-crypt to overwrite a block device, only the default dd block size should be used because dm-crypt's block size is the same (512 bytes), and increasing dd's ...
1
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2answers
894 views

8GB USB disk listed at only 512B or 10MB?

I made an Arch Linux ISO USB drive, and I'm trying to restore it using the directions from the Arch Linux wiki. After running: $ sudo dd count=1 bs=512 if=/dev/zero of=/dev/sde && sync ...
2
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2answers
64 views

Compare two files, while overriding second file's size

I am trying to verify a backup that I made using the following command: dd if=/dev/sda of=/dev/sdc2 I backed up the contents of /dev/sda (internal hard drive) to /dev/sdc2 (external backup drive, ...
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0answers
709 views

Restore errors: “bad header/extent: invalid magic - magic 1701”

I'm testing these instructions to restore a backup image to an Intel Edison from a previous .img image. The backup line was: dd if=/dev/mmcblk0 of=sd/ubilinux_image.img I removed a file (to see if ...
5
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2answers
903 views

Why is dd reading from and writing to the same disk?

I've been using dd in Linux to overwrite an external USB hard drive. When I use the default block size of 512 bytes, with this command: # dd if=/dev/zero of=/dev/sdb throughout the whole operation, ...
1
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3answers
474 views

Copy content from files X and Y to create file XY but XY content is all lowercase

What's the right command to copy the content from file X and File Y to create a new File XY with all letters being lowercase?
7
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1answer
1k views

How does cat 'know' the optimum block size to use?

From reading this, it seems that when copying data to a different hard drive, cat automatically uses the optimum block size (or very near it). I wonder how it determines the optimum block size, and ...
6
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3answers
11k views

Using dd to clone a disk while mounted - risks?

I want to clone a hard disk using dd. Because I want to keep a process on the machine alive continuously, I would like to do this while the filesystem is still mounted. I understand this is not the "...
0
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1answer
101 views

How to recover a node/content from a tarfile that's been overwritten

Disclaimer: I'm not very good at writing questions, and mine is a very specific scenario. So I'm just going to jump straight into the situation: I was browsing my filesystem, and somehow managed to ...
0
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1answer
722 views

Pretty print output of “kill -USR1”-ing dd

When dd is done it prints a three line summary about the number of read and written segments, the total size and average writing speed. While it does its work, dd is awfully quiet. Not too long ago (...
0
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1answer
574 views

USB key does not show up in /dev

We use a USB key system that are contain license files and are provided to unlock proprietary software that we used. The USB drives are small however and get lost easily, so I thought I'd clone them ...
4
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3answers
966 views

How do I DD over the network to an external HD?

I'm trying to clone a hard drive on my raspberry pi which is on the same network to an external harddrive of the computer I'm currently on. However I'm having issues piping the command correctly. I've ...
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2answers
1k views

Faster way to DD?

I am trying to DD a raw file to an SSD from a spin usb spin drive. I have tried compression (but it obviously has to expand before it can copy). I have watched the details of the arm7 gb ram device, ...
2
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1answer
3k views

How to fix BTRFS superblock error after resize/shrink (BTRFS: couldn't get super buffer head for bytenr 274877906944)

BTRFS RAID1 array with 2 500 GB hdds, no errors. This is the root filesystem, so there are 3 partitions on each drive: 1 = /boot (ext4), 2 = / (btrfs), 3 (swap) /boot is ext4 because upgrading the ...
16
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3answers
6k views

What does the two numbers mean respectively in dd's “a+b records” stats?

The first 2 lines in dd stats have the following format: a+b records in c+d records out Why 2 numeric values? What does this plus sign mean? It's usually a+0, but sometimes when I use bigger block ...
2
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1answer
1k views

How to prevent dd from freezing my system?

I want to fill the free space on my hard drive with a command like that : # dd if=/dev/zero of=z but it causes GNOME to freeze regularly for a few seconds. Even the mouse cursor is affected. How ...
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2answers
4k views

How to backup and restore to different hardware in Linux? [duplicate]

I am running Fedora 22 on a Dell Laptop. I plan on migrating to a desktop soon which will also run Fedora 22. What is the best way to go about backing up and restoring my laptop configuration to the ...
1
vote
1answer
152 views

Cloning and remounting sd card

I have a micro sd card that contains these partitions: Disk /dev/sdb: 29,7 GiB, 31914983424 bytes, 62333952 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / ...
11
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3answers
45k views

How to fix this I/O error on a SD card?

I tried with gparted, it didn't work. I found a SDFormatter, tool for windows that did the full erase. I have a SD card and want to install Debian onto it. The dd process takes about 45 minutes, ...
1
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1answer
3k views

The dd command fails with an “Input/output” error while burning a USB stick

This question is somewhat related to the previous question I asked regarding the dd command, The dd command isn't appear to accomplish anything. I'm trying to burn the Ubuntu operating system ...
1
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3answers
3k views

The dd command isn't appear to accomplish anything [closed]

I'm currently trying to burn the Ubuntu operating system onto a USB flash drive of mine, so I can boot onto Ubuntu with my Chromebook. In order to do this, I executed the following dd command: sudo ...
2
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2answers
1k views

HDD cloning and non-matching checksums

I've been trying to clone a 1Tb HDD to a 1Tb SSD following the instructions here. I tried cloning it several times with both dd (painfully slow) and cat (far quicker) but when I came to do checksums ...
2
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1answer
581 views

Accidentally ejected sd card physically while dd

Full cat /proc/partitions + lsblk + fdisk -l output is here: http://pastebin.com/jYCCmwsU I just bought my new class10 16GB SDCard and I started to restore the Raspbian system for the Raspberry with ...