Can I dd from my current hard drive to another hard drive while running the OS

Question

My initial thought is that this is a bad idea.

But let's assume that I can't take a USB stick into my lab to run a live-Linux distro, and my computer has only 2-SATA ports. I have one 80GB SATA drive that I want to dd to my new 1TB drive.

Both drives will take my only 2 SATA ports, I have no IDE ports, I have no USB CDROM drive, and cannot use a USB stick.

Is it a bad idea to try to dd from a running OS to a new drive? Will the drive boot? I can format/partition the extra free space later, I just need to know if my new drive will boot before I begin the process.

Answer 1

It might boot, it might not. As you already figured, it's a bad idea. The contents of the disk might be changing as you read it.

I would rather try to set up a working system on the second drive while your system is running. Then boot into that new system and copy over the data.

Answer 2

Whether it boots or not (and it probably won't), you won't have a working system if you use dd this way.

Your best bet is probably to partition the new 1TB drive: set up a small partition and install a minimal OS on it, boot from that, then image the old drive to the larger partition of the new drive.

Answer 3

DD doesn't care so the short answer is , yes you can but as others have said it's extremely unlikely to achieve what you want to do. Some backup solutions such as acronis can take a snapshot of an online system and then recover the image to a new drive. It's likely to perform better also due to being efficient about free space.