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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Create image from SSD with I/O errors (lemmy.world)

submitted 11 months ago* (last edited 11 months ago) by [email protected] to c/[email protected]

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I have an SSD from a PC I no longer use. I need to keep a copy of all its data for backup purposes. The problem is that dd reports "Input/output error"s when copying from the drive. There seem to be 20-30 of them in the entire 240GB drive so it is likely that most or all of my data is still intact.

What I'm concerned about is whether these input/output errors can cause issues in the image outside of the particular bad blocks. How does dd handle these errors? Will they be eg zeroed in the output or will the simply be missing? If they are simply missing will the filesystem be corrupted because the location of data has been shifted? If so, what tool should I be using to save what can be saved?

EDIT: Thanks for the help guys. I went with ddrescue and it reports to have saved 99.99% of the data. I guess there could still be significant loss if the 0.01% happens to be on filesystem structures, but in this case maybe I can use an undeleter or similar utility to see if I can get back the files. In any case, I can work at my leisure now that I have a copy of the data on non-failing storage.

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[–] [email protected] 26 points 11 months ago (1 children)

Try ddrescue? That's usually pretty good at retrying repeatedly to read dodgy sectors.

You may not be able to recover these sectors, re-reading from failing NAND isn't always as easy as just re-trying a failed sector on an HDD, so once you've got your image you'll probably have to do some filesystem repair on it. Be sure you keep a clean copy of the image and do your repair against a copy of that, otherwise you're at risk of corrupting your only copy further.

[–] [email protected] 4 points 11 months ago

This is exactly what you should do. Additionally, don't forget to use a map file. Check the man page for information about this.

With platters, you can sometimes attempt to freeze a disk in a ziplock bag (to prevent condensation). NAND is totally different, but it might not hurt to try it, especially if you have some cold solder joints. Do whatever recovery you can without these tricks first, though.

Also, bear in mind that if you have a failing disk, you might get many more failures soon. Make good choices and work quickly to get your backup image.