dd is a traditional utility for binary data copies

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3
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4answers
3k views

Comparison of raw block devices

Is there a utility (or some shell magic) that allows me to compare two block devices? Details: I have one large (0.5 TB) RAID device that I've backed up to a slightly larger SATA device using dd. ...
0
votes
1answer
287 views

Backed an ipod up with dd, how to retrieve all tracks in one go with gnupod?

I have had gnupod for a while. Still haven't figured out how to use it though. I usually just go for gtkpod. So this question, in case anyone had any doubts after reading everything below, is purely ...
3
votes
3answers
410 views

Some basic questions about dd

I'm working on a system of how to back up partitions using dd and have been reading a lot about it. I have a few questions and assumptions that I would like to ask. These may seem a little noob-ish, ...
2
votes
3answers
458 views

Duplicating a hard disk

I'd like to simply duplicate a hard disk drive to another hard disk drive of the same size. I know I can simply do: dd if=/dev/sda of=/dev/sdb (or whatever the names of the drives are in /dev). ...
21
votes
4answers
1k views

What's the difference between these two dd commands?

What's the difference between two dd commands that have different bs and count values, as long as they multiply to the same? For example: dd if=/dev/random of=aa bs=1G count=2 dd if=/dev/random ...
3
votes
3answers
1k views

Is creating a sparse image using dd appropriate for backup/restore from a RAID?

I have two non-networked servers, each with 1.2TB of storage in a RAID5 config on an LSI MegaRaid 9240-8i controller. I have been trying without success to get Symantec Ghost to image one machine to ...
3
votes
2answers
848 views

If I dd a CDROM, then I always get the exact copy of the CDROM?

If I: dd if=/dev/cdrom of=cdrom.iso then I will always get the exact same, bit-by-bitly same image that is the same as the original CDROM? Or are there any methods that prevents copying all the ...
5
votes
2answers
1k views

Red Hat cannot boot after clone with dd

I used dd to clone a x4100 server with Linux Red Hat. The hardware is identical for old and new servers. Disks are sda, sdb and sdc(sdc1 and sdc2). But newly restored server gives following errors and ...
20
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2answers
4k views

When is dd suitable for copying data? (or, when are read() and write() partial)

Short version: In what circumstances is dd safe to use for copying data, safe meaning that there is no risk of corruption due to a partial read or write? Long version — preamble: dd is often used to ...
19
votes
4answers
7k views

Clone whole partition or hard drive to a sparse file

I like to clone a whole partition or a whole hard drive onto a larger external disk but like to create a sparse file. I often use dd for cloning, but it doesn't support sparse files. As a workaround I ...
5
votes
3answers
5k views

How can I make a bootable usb flashdrive?

Can I just dd an Ubuntu 11.04 mini.iso to an usb flashdrive an boot from it? or what am I missing?
56
votes
7answers
8k views

dd vs cat — is dd still relevant these days?

I recently realized we can use cat as much as dd, and it's actually faster than dd I know that dd was useful in dealing with tapes where block size actually mattered in correctness, not just ...
3
votes
7answers
1k views

How to write repeated free-form strings to a file, as fast as 'dd'?

dd can write repeating \0 bytes to a file very fast, but it can't write repeating arbitary strings. Is there a bash-shell method to write repeating arbitary strings equally as fast as 'dd' (including ...
56
votes
10answers
30k views

How do I know if dd is still working?

I've not used dd all that much, but so far it's not failed me yet. Right now, I've had a dd going for over 12 hours - I'm writing an image back to the disk it came from - and I'm getting a little ...
29
votes
4answers
12k views

Is there a way to determine the optimal value for the bs parameter to dd?

On occasion I've seen comments online along the lines of "make sure you set 'bs=' because the default value will take too long," and my own extremely-unscientific experiences of, "well that seemed to ...
26
votes
6answers
17k views

Best way to remove bytes from the start of a file?

Today I had to remove the first 1131 bytes from an 800MB mixed text / binary file, a filtered subversion dump I'm hacking for a new repository. What's the best way to do this? To start with I tried ...
16
votes
4answers
6k views

What does dd stand for?

I know very well what the command does, but man dd, info dd tell me: 'Convert and copy a file', as does GNU Coreutils. Google says its an abbreviation of everything between medicine and bad webchat ...
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votes
5answers
5k views

How do I suppress dd output?

I have a bash script that creates some file using dd. The problem is dd throws a great amount of output that is going to mess with the output of my script. Searching around I've found a solution: dd ...
11
votes
3answers
1k views

saving data from a failing drive

An external 3½" HDD seems to be in danger of failing — it's making ticking sounds when idle. I've acquired a replacement drive, and want to know the best strategy to get the data off of the dubious ...
1
vote
2answers
663 views

“lshw -C disk” returns but prints nothing

I am using an ubuntu live cd to help me recover some data off of a hard drive. I used lshw -C disk to find out which device I need to copy, /dev/sda in this case. I am using ddrescue -n to try and ...
10
votes
1answer
15k views

How do I mount an `img` created with /bin/dd of a hard drive?

I used dd to backup a 80GB drive dd if=/dev/sdb of=~/sdb.img Now I need to access some files on that drive, but I don't want to copy the ".img" back over the drive. mount ~/sdb.img /mnt/sdb ...