Linux how long does dd take

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Whether you are a digital nomad or just looking for flexibility, Shells can put your Linux machine on the device that you want to use. Click here for more info. 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.

Very nice question. The raw interface is implemented on some unix systems tru64,hpux,solaris but not on linux. The short answer is : NO it is not implemented,at least as far as I know. I am using linux since the old times of kernel version 2. Sign up to join this community. The best answers are voted up and rise to the top.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why dd takes too long? Ask Question. Asked 5 years ago. Active 1 year, 9 months ago. Viewed 35k times.

Improve this question. Why would you use dd here? Also, what hardware, etc, yaddayadda. Welcome to dd pitfall 1 — Dmitry Grigoryev. Show 3 more comments. Active Oldest Votes. Regarding rdsk , the sd 4 man pages say: At this time, only block devices are provided. Improve this answer.

Khirgiy Mikhail 1 1 silver badge 5 5 bronze badges. Basile Starynkevitch Basile Starynkevitch 9, 28 28 silver badges 49 49 bronze badges. Whether rdsk is available in Linux systems? I have used in Unix systems. The page cache will probably deal in 4Kb blocks whatever you do, but you can control how many syscalls dd uses to read that 4Kb. I'm sure there's some read size above which the cost of stalling writes is more expensive than the saved syscalls, but have no idea where the sweet spot is.

A block size of a few MB is better than the default B but when I benchmarked this I found that cat did just as well for filesystem-to-filesystem transfer, direct block-to-block may have different performance characteristics.

However the difference wasn't dramatic in any case. Show 4 more comments. However the current root device isn't necessarily sda. I've had workstations where, for various reasons, the root was sdb or even higher. How to use dd in Linux without destroying your disk How to use dd in Linux without destroying your disk. Safely and reliably make perfect copies of drives, partitions, and filesystems with the Linux dd tool. Image by :. Get the highlights in your inbox every week. Making perfect copies of drives and partitions More Linux resources.

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