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Data recovery and disk repair questions and discussions related to old-fashioned SATA, SAS, SCSI, IDE, MFM hard drives - any type of storage device that has moving parts
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ddrescue errors

April 19th, 2011, 1:46

When using ddrescue to scan an HDD and it displays the number of errors, how can you know if any given error count is acceptable, and the drive still usable?

Is the drive considered unusable if ddrescue is unable to read a certain number of sectors ?

If so what is that number ? Does it depend on the capacity of the drive ?

Re: ddrescue errors

April 19th, 2011, 3:32

If you are using ddrescue on a drive then the reason you're probably using it is because the drive already has errors and you are having trouble accessing it. The fact that it gives errors means that there's an issue (small or large) with the drive. I would never trust my data to a drive that has issues. With drives being so cheap these days just get yourself a new one and make sure you have backups backups backups.

Re: ddrescue errors

April 19th, 2011, 9:25

Nick_CT wrote:I would never trust my data to a drive that has issues. With drives being so cheap these days just get yourself a new one and make sure you have backups backups backups.

I agree completely

Re: ddrescue errors

April 19th, 2011, 18:07

OK I see.

One more question.

Is the error count in ddrescue a count of INDIVIDUAL unreadable sectors, or "blocks" of unreadable sectors.

Re: ddrescue errors

April 20th, 2011, 10:12

"Press F4 again to start the scan. MHDD scans drives by blocks. For IDE/SATA drives one block is 255 sectors (130560 bytes). "

Re: ddrescue errors

April 20th, 2011, 12:19

tech_boy wrote:Is the error count in ddrescue a count of INDIVIDUAL unreadable sectors, or "blocks" of unreadable sectors.

Yes :) or even a combination of the two. The answer depends on how you are using ddrescue and when in the process you look at that count.

Think about the default algorithm used by ddrescue (which you can influence with command line options, and often need to do so for best results). You'll see that during that process, ddrescue has different information available to it, at different times.
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