This article will help in case of VHD issues and want to take a backup of VDI if the command xe vdi-copy doesn't work. This is an advanced tutorial and execute the command with care

Instructions

1. Create a new VDI as of the same size of the source VDI

1. Make sure the LV for the VDI are active by running

#lvchange -ay /dev/VG-XenStorage-SR-UUID/VHD-VDI-UUID

1. Create the tapisk process for those VDI

Source 

#tap-ctl create -a vhd:/dev/VG-XenStorage-SR-UUID/VHD-VDI-UUID -d /dev/xen/blktap-2/tapdev2 

Dest: 

#tap-ctl create -a vhd:/dev/VG-XenStorage-SR-UUID/VHD-VDI-UUID -d /dev/xen/blktap-2/tapdev3 

1. Confirm with fdisk -l /dev/xen/blktap-2/* 

1. Perform the dd operation to perform block level copy

do the dd using: 

# dd if=/dev/xen/blktap-2/tapdev2 of=/dev/xen/blktap-2/tapdev3 bs=1M iflag=direct oflag=direct 

1. Once copied, you need to close the tap disk connection to both the source and destination: 

   #tap-ctl list (will show you the pid and the minor number) 

   #tap-ctl close -p id -m   (for both source and set)