When copying VM filesystem over netcat, dd copies double the disk size

Posted by JivanAmara on Server Fault See other posts from Server Fault or by JivanAmara
Published on 2014-08-22T20:20:28Z Indexed on 2014/08/22 22:23 UTC
Read the original article Hit count: 239

Filed under:

virtualbox

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dd

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netcat

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knoppix

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vmware-vcloud-director

I'm attempting to copy the disk of a working headless virtualbox VM (VM1) on one server to a new VM (VM2) on a vCloud server. I don't have access to the host of VM2. The OS is Windows Server 2003 (32-bit)

I start both VMs with a live Knoppix image.
I run 'nc -l | dd of=/dev/sda bs=512' on VM2
I run 'dd if=/dev/sda bs=512 | nc ' on VM1

I previously did this with another windows VM and it worked fine.

VM1 has a disk of size ~70GB (verified with fdisk); however, the amount of data dd reports read/written is ~139GB.

Of course the target machine doesn't work properly. I get a Windows splash screen, then blue error screen with general 'system not working' information.

I'm at a loss what could cause this. Any ideas?

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