I'm copying an entire HDD using the dd tool, and I'm considering stopping part of the backup due to space limitations.

Does the dd tool begin at the front of a partition when copying? The first ~90 GB are the relevant parts as they contain boot information, everything else can be ignored if necessary.

I could not find this information in the manpages.

  • 1
    Yes it does. At least when I tried. However I am not sure that it may be taken for granted on all systems and don't know how to limit its backup. Notion of the start of partition breaks particularly easy on more exotic RAIDs and LVMs or similar.
    – IBr
    May 2, 2014 at 12:38
  • Thanks! This is very helpful. I read the dd manual and did not find anything.
    – Qu0rk
    May 2, 2014 at 13:03

1 Answer 1


Warning: with dd you can destroy data very easily, make sure you have backups and are familiar with dd before using it

dd starts copying from the first byte of the disk you specify, including the master boot record, mbr. For example http://www.cyberciti.biz/faq/howto-copy-mbr/

dd if=/dev/sda of=/tmp/mbr.bak bs=512 count=1

This will copy the first 512 bytes of your hdd (in this case sda). This data is before the first partition.

You can change bs=512 count=1 to something like count=90G http://maarten.lippmann.us/?page_id=116

If you only want to copy boot info however this may be too much data, in general boot information would not be that big.


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