The copying direction is reversed after each pass until all the rescue domain is tried. Copying phaseĬopying is done in up to five passes. Trimming, scraping, and retrying are done sector by sector.Įach sector is tried at most two times the first in the Copying phase as part of a large block read, the second in one of the phases below as a single sector read. Only non-tried areas are read in large blocks at Copying phase. Without a mapfile, you will have to start over again! This allows you to resume an interrupted image at the point you left off, or to retry bad sectors after an initial pass. Output.mapfile is the name of the mapfile. Output.img is the name of the image file. Naturally, if you just wanted a specific partition, you would use something like /dev/sda1 instead. dev/sda is the drive we are rescuing…the whole disk. You can always use the mapfile to go back and retry the bad sectors after you get an image from the first sweep. Note: On a failing drive you may want to eliminate this option the first time so as to not waste time hammering on bad sectors and risking drive failure. r3 tells ddrescue to retry bad sectors 3 times before giving up. cpass=0 skips the copying phase entirely. To run only the given pass(es), specify also -no-trim and -no-scrape. cpass selects what pass(es) to run during the copying phase. Note that this option does not specify the size of the resulting outfile. If ddrescue can't determine the size of the input file, you may need to specify it with this option. It limits the amount of input data to be copied. s bytes defines the maximum size of the rescue domain in bytes. (For example, if you pass the option '-reverse' to ddrescue, it starts copying from the end of the rescue domain). This is not the point from which ddrescue starts copying. i bytes defines the starting position of the rescue domain in infile, in bytes. d tells ddrescue to use direct disk access and ignore the kernel’s cache. Hdiutil attach output.img -shadow output.shadow
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