I've run into an issue where I need to make an image of a decent sized USB drive. The only place where I have enough room to store that image is on my iMac. The issue is this drive has FAT32 and EXT4 partitions. So I searched and found this question on Ask Different. That question is closed in favor of another question with this answer by @Ian C.
Granted, it's an excellent answer, but, since the first question has no answers and has been closed, I am still no farther along in finding my answer than I was 10 minutes ago, after starting the search and looking into the issue of this question being closed. Without wanting to spend more time doing a deep dive into the history of the closed question, I find the closing of the question (or the keeping of it closed with a clear explanation why it's not a duplicate) either hasty or superficial.
The answer does say:
Now you've got a bit-wise perfect clone of your Macintosh HD drive.
That sounds authoritative, but if you have a question like the one that's closed, reading this answer does leave open room for interpretation: Is it only a Mac drive that gets cloned (since most of us know "Macintosh HD" is the name given automatically to a Mac system drive)? Does it read the partitions that macOS can't recognize? Or does it copy every bit on that entire device, whether the partition is readable by macOS or not?
I get that a lot of people have the technical background that they'll read that and say, "It's obvious." I don't think so and it seems that the person (@sekizuri) is unsure if it does and states it in his question and in one of his comments. After all, isn't one of the goals of this site to address answers for those who aren't as technically advanced as others may be? My impression is Ask Different is not designed for people with a certain skill level and above (other than at least knowing how to plug in a Mac and use the mouse and keyboard).
So sekizuri and I both do not, at this point, have an answer, and if the question were left open, we might. This question should not have been closed and I wonder if it was closed by those who do not get the distinctions I've pointed out.
I think this could be easily fixed in several ways, but all would need to be from someone who knows the answers and not from someone just trying to fix it or close the issue so it goes away:
- Re-open the question so it can get a precise answer that leaves no doubt
- Have someone who knows dd well specify the answer in a comment on that question
- Edit the answer on the other question to add language to spell out that "bit for bit" does mean it includes partitions macOS can't read
- Add that info in one of the comments on that answer, or
- Add that info to one of the comments on the closed question.
My entire point at raising this issue, and spending enough words on it to try to be clear and specific, is that the closed question does not have an authoritative answer. The fact that I searched for something that's almost exactly what that question is about and that I still don't have an answer shows that gap.
dddoes actually allow for coping partitions that macOS can't actually read natively. With one caveat: the partitions and drive must not be in use. I updated the final paragraph in the answer. Solid ask there, thanks for raising it!