Dd zero how long

However the difference wasn't dramatic in any case. Show 4 more comments. Specifically, the reason dd had to be used was a bug in GNU cp and a bug in the linux kernel in the early 90s. The reasons for using dd on historical unix systems was very different, and wanting to copy a whole block device was an unusual thing to want to do. Random wanting to copy an entire disk would have been unusual, but I do remember needing to copy partitions around big ones - or even MB — roaima.

The specifics of the bugs: the kernel reported disk usage sizes incorrectly [leading cp to conclude that every source file was a sparse file], and cp did not zero out blocks when copying from a sparse file to a device destination.

So any zero block in your source would have whatever garbage happened to already be on the disk — Random I love this kind of answer. Thanks for the info. Here's your updoot. Add a comment. In Ubuntu, you can install it with: sudo apt-get install gddrescue and just plain ddrescue to use. G-Man Says 'Reinstate Monica' Roger Heathcote Roger Heathcote 3 3 silver badges 8 8 bronze badges. In the Debian repo's it's called 'gddrescue' but once it's installed you just type 'ddrescue' to run it. It's called that because it's full name is 'GNU ddrescue' and there was some different package called 'ddrescue' already.

Erik 1 1 silver badge 4 4 bronze badges. Why do you suggest a block size which is not a power of two? Basile a multiple of the disk block size is sufficient, so 20MiB would be fine. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming Featured on Meta.

Now live: A fully responsive profile. Linked Related 0. Overwriting the partition table as you do in your first step is sufficient to frag the partition table. If you're installing an OS on the drive afterwards, overwriting the entire drive with zeros is pointless.

Then it's simple math. If it's USB 3, it'll be faster. If it's SATA, it'll be faster still. But without specific performance characteristics, it'd be difficult to estimate. Why do you want to zero a new disk? I would understand you'd want to zero the old disk, not the new. But then, I would not understand why partition the old disk. And in any case, new or old, why create random partitions on it, and delete them Shouldn't be needed if you're simply re-using a disk which has had data written to it, when you create new partitions and format, the "pointers" to data are all changed so the previous data is normally inaccessible but recoverable with proper tools until overwritten, and maybe even over-written numbers of times.

But, answering your main Q, The dd command takes "forever" if you copy only one byte at a time. You can speed things up by specifying larger blocks eg I keep the following in my toolbag which describes two ways of using dd to zero space. Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here!

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Doing a complete backkup of one drive to another, creating a duplicate. I have used this before on a 40GB drive. This time I'm doing a GB drive - does anyone have an wild guess on how long it should take?

Click here to see the post LQ members have rated as the most helpful post in this thread. Hi, the exact time will depend on the speed of your harddisks. Are they external USB harddisks? Both internal? You can calculate the time with the following formula: Code:. Perfect, thank you. The command prompt has not returned, so it appears to still be copying. Although I have heard that sometimes this happens, even though it has completed.

It has been going now for 13 hours, so I will stop it and see if I have a good copy. Originally Posted by masontech compren. Last edited by crts; at AM. Thread Tools.