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I am trying to copy (using dd) from one hard drive to another on a network of only two computers (a Ethernet cable between them). The computers are the same model and the hard drives are also the same model. I cannot copy to a different hard drive it must be to the destination hard drive. Since somebody decided rsh is not safe I am using dd over ssh (rsh was a lot faster for this type of transfer). In the past I had no problems doing this.

root@192.168.38.110 "dd if=/dev/sda bs=2048 of=/dev/stdout" | dd if=/dev/stdin bs=2048 of=/dev/sda

The copy seems to work but gpart complains about the copied partition table, "physical block size is 2048 bytes, but Linux says it is 512”

The bs=2048 in dd seems to do nothing.

How can I do a copy with a different block size?

  • bs= refers to how many bytes dd process at a time (writes and reads are faster if you give Linux more data at a time). gparted complains about the partition table not being generated for the disk in question. Consider partitioning the new drive as you want it, and then copy each partition by itself. The rsh not being safe can be fixed by unplugging the network router while you do this. – Thorbjørn Ravn Andersen Oct 25 '17 at 22:19

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