What's the meaning of: /dev/rdisk0s1 and /dev/rdisk0s2s1?

Question

I'm trying to use SSH to make a disk image by using DD on an iPod.

And I'm using this commands:

ssh root@192.168.1.100 dd if=/dev/rdisk0s1 bs=1M | dd of=iphone-root.img

ssh root@192.168.1.100 dd if=/dev/rdisk0s2s1 bs=1M | dd of=iphone-user.img

What's the meaning of: /dev/rdisk0s1 and /dev/rdisk0s2s1? It seems they're references to places in the disk, how can I know how many places are in this disk?

Answer 1

I don't know much about iphone but dd to make an image of a mounted partition of a running system? That's usually a pretty bad idea. If this partition is written to in the middle of the operation you'll most likely end up with an inconsistent image.

Not sure what you're trying to achieve but unless you're making an image of an unmounted partition, I can't see what this could be good for due to the above reason.