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Cake day: Jun 18, 2022

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I generated a domain_logfile with > ddru_ntfsbitmap /dev/sdc1 ddru_ntfsbitmap.mapfile (This way ddrescue knows, which blocks are empty and don't need to be read) Then I ran ddrescue: > ddrescue --sparse --domain-mapfile=ddru_ntfsbitmap.domain_mapfile /dev/sdc1 sdc1.img mapfile But after a very short time ddrescue froze and I disconnected the drive. This is an excerpt from the log: https://danielhammocks.uk/Collabin/#18092022KLBkvwn1 I tried it again: > ddrescue --no-scrape --no-trim --idirect --sparse --domain-mapfile=ddru_ntfsbitmap.domain_mapfile /dev/sdc1 sdc1.img mapfile it froze again. Then I tried different --input-positions, So that I could overcome the part on the HDD, which caused the freeze: ``` ddrescue --no-scrape --no-trim --idirect --sparse -i 3333 --domain-mapfile=ddru_ntfsbitmap.domain_mapfile /dev/sdc1 sdc1.img mapfile ddrescue --no-scrape --no-trim --idirect --sparse --input-position 3333 --domain-mapfile=ddru_ntfsbitmap.domain_mapfile /dev/sdc1 sdc1.img mapfile ddrescue --no-scrape --no-trim --idirect --sparse --input-position 993333 --domain-mapfile=ddru_ntfsbitmap.domain_mapfile /dev/sdc1 sdc1.img mapfile ddrescue --no-scrape --no-trim --idirect --sparse --mapfile-interval 30s --timeout 2m--input-position 993333 --domain-mapfile=ddru_ntfsbitmap.domain_mapfile /dev/sdc1 sdc1.img mapfile ddrescue --no-scrape --no-trim --idirect --sparse --mapfile-interval 30s --timeout 2m --input-position 993333 --domain-mapfile=ddru_ntfsbitmap.domain_mapfile /dev/sdc1 sdc1.img mapfile ddrescue --no-scrape --no-trim --idirect --sparse --mapfile-interval 30s --timeout 1m --input-position 99999999999 --domain-mapfile=ddru_ntfsbitmap.domain_mapfile /dev/sdc1 sdc1.img mapfile ``` That last one worked and finished: ```(sizes limited to domain from 97_667_704Ki B to 976_750_976Ki B of 976_750_976Ki B) rescued: 0 B, tried: 0 B, bad-sector: 0 B, bad areas: 0 Current status ipos: 1000 GB, non-trimmed: 0 B, current rate: 393 kB/s opos: 1000 GB, non-scraped: 0 B, average rate: 125 MB/s non-tried: 0 B, bad-sector: 0 B, error rate: 0 B/s rescued: 866603 MB, bad areas: 0, run time: 1h 55m 3s pct rescued: 100.00%, read errors: 0, remaining time: n/a time since last successful read: n/a Copying non-tried blocks... Pass 1 (forwards) Finished ``` I compared the mapfile I got from ddrescue with the one I generated from the ntfs filesystem and was shocked to see that there was an offset. The ddrescue mapfile: ![The ddrescue mapfile](https://federated.community/pictrs/image/b0d42abb-9b37-4954-b047-f9360b0c86d9.png) There the Block is 6718 The ntfs mapfile: ![The ntfs mapfile](https://federated.community/pictrs/image/877fdfe2-7272-4ab0-a395-519c96e0289c.png) and here the block is 8817. But both report the same Start 0x123BAAE000 and Length. I compared the two mapfile outputs and there are some differences: https://www.textcompare.org/?id=62adebff3cb0dd7a1816303b (thanks @Zerush[@Zerush@lemmy.ml](https://lemmy.ml/u/Zerush) for the recommendation of textcompare ) However other parts are identical. --- # Now to my Questions:D Is this offset bad? Can I continue to use ddrescue and try to get the remaining parts, where ddrescue froze? How can and should I correct it? Whats the cause? I read that > Modern [HDDs] tend to handle the simple BadBlocks automatically, for example by writing a disk sector that was read with difficulty to another area on the media. [...] such a remapping can be done by a disk drive transparently https://www.smartmontools.org/wiki/BadBlockHowto Was the slow freezing of ddrescue caused by the drive trying to read bad blocks and reallocating them somwhere else? Was it stupid to unplug the USB-HDD while ddrescue was freezed? Did this cause the mismatch of the mapfile I generated from ntfs with the one generated during the ddrescue run? Or was the mismatch caused by the input-positions not aligning to the Blocks on disk? Or because I used the `--sparse` option, so 0 values will be compressed on disk? (This was my source, on how to use ddrescue: https://wiki.ubuntuusers.de/gddrescue/ )
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