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On 2017-03-01 00:06, Greg Freemyer wrote:
dd_rescue and ddrescue are both designed to work with dieing disks. I forget which is which, but one of them at least when it hits a bad block will jump ahead and leave a gap, Then when it finishes the first pass (including gaps), it comes back and tries to get all the missing pieces. It can make 5 or 10 passes (or more) trying to get a complete copy. The log is used to keep track of what it still needs to get, so you keep passing the same log file to it every time you call it for the same disk. One of them comes with a batch script to automate the process. I don't use that one; I prefer to control what it is doing myself.
That will be dd_rhelp. It is a bash script: er@minas-tirith:~> dd_rhelp --help dd_rhelp ver. 0.3.0 Options: --help Print this message --version Print version information {filename|device} The source file (it can be a block device) {output-file} The destination file info Specifying "info" as third argument will display summary informations on ongoing recovery and exit without taking any actions. Note: A log file will be created, and named '<output-file>.log'. This is a dd_rescue log file (which is human readable). This log file is important as dd_rhelp feeds itself with its contents to manage correctly dd_rescue. Without this log file, dd_rescue won't support resume capability. Send bug reports, or comments to vaab@free.fr. cer@minas-tirith:~> The idea is, I think, to call dd_rhelp instead of dd_rescue, same syntax: dd_rhelp input output and forget. Maybe what I said about dd_rescue automatically going round only applies to dd_rhelp.
I've been working seriously with client disks for 10 years and I doubt if I've had to invoke either ddrescue or dd_rescue more than a dozen times combined.
I use them because I can abort and continue, and to prevent lost time if there is a bad sector.
One big reason for that is that if a disk is in that bad of shape, I send it out to a professional recovery lab most of the time. Having ddrescue beat a disk to death can just make the situation worse.
Interesting point. -- Cheers / Saludos, Carlos E. R. (from 42.2 x86_64 "Malachite" (Minas Tirith))