Hi,

I use LVM on top of LUKS.

My entire root file system is on a logical volume. I have no seperate home or swap partitions.

I would like to know how can I clone this logical volume to my external hard disk. 

I have seen commands like :

dd if=/dev/vg/root_lv of=/mnt/exthdd bs=64k conv=noerror,sync status=progress

I have a couple of questions about this:

1) Why use noerror and sync?

noerror might give me a corrupted image and sync is just going to increase the size of my image with padding. 

Why use them?

2) What is rationale behind block size? 

Will using 4M block size instead of 64K give me a different image?  I need my image to be an EXACT COPY.

Need your help. 

Thanks.