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I will be backing up a large (750GB) disk to an external USB disk using dd.
What is the most appropriate use of notrunc, noerror and sync conversion arguments? It seems some people use them in different ways, or not at all.

Also, what is the best block size? USB is likely to be the bottleneck here.

dd if=/dev/sda bs=1M | gzip -c > /mnt/sdb1/backups/disk.img.gz

gzip -dc /mnt/sdb1/backups/disk.img.gz | dd of=/dev/sda bs=1M

Thanks.

mcu
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1 Answers1

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Avoid using dd; programs like ddrescue have a much better status reporting, imply noerror, and conversion is not desired on disk images at all.

jørgensen
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  • Good catch. `ddrescue` looks more robust then plain `dd`. Would you use GNU `ddrescue` or `dd_rescue`? What is a good Live CD to download? I would be nice to have GParted + ddrescue + dd + a good collection of drivers on one CD. – mcu Mar 12 '12 at 20:51
  • GNU ddrescue has practically superseded Knorr's dd_rescue and also has thankfully done away with requiring an ugly dd_rhelp script. – jørgensen Mar 12 '12 at 21:10