Re: dd if=/dev/rdisk12 of=/dev/zero (OT, since macOS)
Date: Sat, 01 Nov 2025 22:12:11 UTC
Christophs-MBP:~ root# ls -al /dev/rdisk12 crw-r----- 1 root operator 0x100001e Nov 1 23:02 /dev/rdisk12 Christophs-MBP:~ root# dd if=/dev/rdisk12 of=/dev/null dd: /dev/rdisk12: Invalid argument 0+0 records in 0+0 records out 0 bytes transferred in 0.000052 secs (0 bytes/sec) Christophs-MBP:~ root# > The drive is new and I haven't done nothing else than mounting it on my macOS. Never written to it. My suspicion is that it is fake hardware. Einar, die idea that I /dev/zero is wrong for using in the output direction just came to me a couple of minutes before, but it didn't change anything. Paul, I just wanted to read every byte from the drive into the kitchen sink. After that dd would write out the number of bytes read. That should be 10.485.760.000.000 Bytes > Am 01.11.2025 um 16:43 schrieb Einar Indridason <einar.indrida@gmail.com>: > > try using /dev/null as your output. instead of /dev/zero > > On Sat, 1 Nov 2025, 15:08 Christoph Kukulies, <kuku@kukulies.org <mailto:kuku@kukulies.org>> wrote: >> >> No, I don't want to use diskutil. I wanted to know why my dd command returns "Invalid argument". >> Yes, I know it's OT, sorry for that. The suspicion comes up that I'm fallen victim a fake. So I anted to physically read the device once. >> A program like diskutil or system information USB section only transports the faked information. >> >> Is "Invalid argument" already a consequence of the drive being a fake? >> >> -- >> Christoph >> >> >>> Am 01.11.2025 um 16:00 schrieb paul beard <paulbeard@gmail.com <mailto:paulbeard@gmail.com>>: >>> >>> Ah. So you want to verify what 'diskutil info rdisk12' returns? >>> >>> On Sat, Nov 1, 2025 at 7:39 AM Christoph Kukulies <kuku@kukulies.org <mailto:kuku@kukulies.org>> wrote: >>>> No no, direction is intentionally read. I just want to read the disk once to get the exact count of bytes and see its integrity. >>>> >>>> >>>> >>>> >>>> Christoph Kukulies >>>> kuku@kukulies.org <mailto:kuku@kukulies.org> >>>> >>>> >>>> >>>>> Am 01.11.2025 um 15:32 schrieb Odhiambo Washington <odhiambo@gmail.com <mailto:odhiambo@gmail.com>>: >>>>> >>>>> >>>>> >>>>> On Sat, Nov 1, 2025 at 5:10 PM Christoph Kukulies <kuku@kukulies.org <mailto:kuku@kukulies.org>> wrote: >>>>>> Hi co-readers, >>>>>> >>>>>> excuse me for coming up with a non FreeBSD question but I'm sure many "also macOS" users are here. >>>>>> I got an SSD external drive today from China. It's supposed to have 10TB and has the name "SEAGATE" engraved on the cover which I haven't opened >>>>>> yet, also because it's clipped together - no screws. >>>>>> >>>>>> Anyway, I tried >>>>>> >>>>>> >>>>>> # dd if=/dev/rdisk12 of=/dev/zero >>>>>> >>>>>> on it (in a macOS terminal window. >>>>>> >>>>>> I'm getting >>>>>> >>>>>> $ sudo dd if=/dev/rdisk12 of=/dev/zero bs=512 >>>>>> Password: >>>>>> dd: /dev/rdisk12: Invalid argument >>>>>> 0+0 records in >>>>>> 0+0 records out >>>>>> 0 bytes transferred in 0.000036 secs (0 bytes/sec) >>>>>> $ >>>>>> >>>>>> also without the bs=512 not any better. >>>>>> >>>>>> An ideas what might be wrong? >>>>> >>>>> You want to wipe the disk, right? So, you write zeros to the raw device, not the other way round. >>>>> So it should be something like this: >>>>> >>>>> dd if=/dev/zero of=/dev/rdisk12 bs=16M count=1000 status=progress >>>>> >>>>> >>>>> >>>>> -- >>>>> Best regards, >>>>> Odhiambo WASHINGTON, >>>>> Nairobi,KE >>>>> +254 7 3200 0004/+254 7 2274 3223 >>>>> In an Internet failure case, the #1 suspect is a constant: DNS. >>>>> "Oh, the cruft.", egrep -v '^$|^.*#' ¯\_(ツ)_/¯ :-) >>>>> [How to ask smart questions: http://www.catb.org/~esr/faqs/smart-questions.html] >>>> >>> >>> >>> >>> -- >>> Paul Beard / www.paulbeard.org/ <http://www.paulbeard.org/> >>