Many years ago I tried it, but didn’t really read up on it. Wanted to back up my Pi’s sdcard while the system was running. I even fucking named that script “online-backup”.

Now every time I ran that, after hours, I noticed my Pi was crashing, and never booted back up. I used chinese sd cards so I blamed it on them.

But this happened multiple times, just to learn I was using dd absolutely wrong.

dd was always a scary utility to me, and still is. I fucked up things with dd, regardless I quadruple checked everything 😅

but to answer the question; it’s possible, but you really need to know what are you doing.