How DD threat bad sectors when cloning?
How DD threat bad sectors when cloning? Got 500GB HDD that is starting to falling, it is just a system drive no data to backup, will DD make a clean copy of the system when the drive has bad sectors?
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The best you can do is use conv=sync,noerror on the dd command so it leaves empty blocks when it gets an error when reading the input. That way, the blocks on the output HDD end up in the right places.
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The best you can do is use dd as described by catkin and check out ddrescue and dd_rescue. Both offer options not present in 'dd' like reading a disk back-to-front, retrying and copy rate adjusting.
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I hope that using DD will be possible to avoid reinstall the system again(ugh), it is a big install of programs. Regards |
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dd if=/dev/sda of=/dev/sdb bs=512 conv=sync,noerror Regards |
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Ok i got this with Clonezilla !! Not sure what happened with DD but now it is working just fine all partitions has been cloned and running! :) Regards |
manufacturer's disk repair utility, dd, ddrescue, foremost, fsck
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The data can usually be successfully relocated from the failing sectors to extra sectors on the drive used for this purpose. That's the first line of defense. Most drives are not really failing. They just have an imperfect area on one surface platter. My experience has been that running the utility permanently solves the problem, and the drive works for five or ten years more. But, the test can fail if the drive controller is bad. The utility prints a report. dd is not a sophisticated recovery tool. It's my last choice. I've never used dd for data recovery. But dd has an undocumented function. Over time, data tracks expand. This can give bad blocks errors. So, you can write the drive back to itself: dd if=/dev/sda of=/dev/sda That tightens the tracks. ddrescue is better. It contains sophisticated algorithms to read the edges of bad tracks, to repeatedly read the same track and pick up a little bit more of the data with each pass, to read the drive backwards, to guess at the correct contents to fill small unrecoverable gaps within blocks of recovered data, to operate without a valid partition table, but I have seen it fail. foremost is a file carver. It will carve out every file. The problem is it doesn't preserve the file names (uses numbers instead), recovers deleted files, recovers only a small number of file types by default, groups the files in a directory tree according to file type. But I've seen foremost recover everything off a DVD+R that looked like it had been put under a vehicle tire for traction to get out of a snow bank. I had a CD that I scored with deep knife cuts for disposal, but I messed up. Then I had to recover the data. Foremost can recover everything from a disk like that. The moral is, it takes a bit of work and ingenuity to render a CD safe for disposal. Everything has some risk, but fsck has a map and relocate bad blocks function that gives you an idea of what eternity might be like, but it's one of the safest remedies. You choose based on how critical the operation is. |
Awsome!
This thread really helps me a lot.
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very nice post on dd
Thanks for this nice educative post. I just wonder can anyone give a reason why dd if=...iso of=/dev/sdb to create a bootable flash works sometime and sometime not. It seems a powerful command but it doesnot work sometimes where MS Windows programs like lilo (great app though) work on same flash drive and same iso.
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Copying an ISO image to a disk using dd is only possible if the ISO image is a hybrid-ISO.
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if you run the file command it will tell you if your iso is a partition or an image of a full disk including boot sector and partition table (judging by your example command you are expecting the latter). |
DD post..
Thank you for writing that post. I am tired and needed to go to sleep a while ago but reading that kept me up and caused me to register on this site and post.
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U3
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