Would it help to add iflag=direct and/or oflag=direct? -T
On Tue, May 1, 2018, 2:42 PM Russell Senior <russ...@personaltelco.net> wrote: > Followup on this, I noticed it again last night on multiple USB > thumbdrives. A dd to the device immediately succeeds (which is weird in > itself for large writes of iso sized blobs), but unplugging-replugging > shows the writes didn't actually happen. The problem was persistent until I > rebooted the machine and it started working normally again. Very weird. I > think the microSD was probably fine and the hosage was at the USB or > something other than the hardware level. It might be related to unplugging > a mounted device at some point. Any ideas are welcome. > > On Tue, Mar 6, 2018 at 8:29 PM, Russell Senior <russ...@personaltelco.net> > wrote: > > > https://www.youtube.com/watch?v=r3GDPwIuRKI > > > > On Tue, Mar 6, 2018 at 8:22 PM, Russell Senior > > <russ...@personaltelco.net> wrote: > > > Yeah, I understood about the on-SD controller. There is typically > > > some kind of ARM-based microcontroller that does all the block-device > > > to NAND translation. It is doing something wrong and clearly > > > dysfunctional now, though. I am sure that I did successful block > > > operations on the same microSD previously. > > > > > > On Tue, Mar 6, 2018 at 5:31 PM, Tomas Kuchta > > > <tomas.kuchta.li...@gmail.com> wrote: > > >> When I said card controller, I meant the card controller on/in the > > actual > > >> SD card. Not the piece of HW attached to your computer. > > >> > > >> My conclusion at the time I was trying to understand the same behavior > > was > > >> that the in-card controller must be doing file transactions of some > > kind. > > >> Not behaving quite like basic block device. > > >> > > >> I recall even trying to actively corrupt the card's content, no > success. > > >> Still, all worked fine when installing Linux on said cards. > > >> > > >> Hope it helps you avoiding wasting whole day or three on this, like I > > did. > > >> > > >> Tomas > > >> > > >> On Mar 7, 2018 9:23 AM, tomas.kuchta.li...@gmail.com wrote: > > >> > > >>> I do not believe that SD cards respond to pure raw block writes from > > dd. > > >>> Not unless the stream looks like files. > > >>> > > >>> I run into the same discovery some time ago. If I remember correctly, > > dd > > >>> didn't overwrite the content even with random data. It could behave > > >>> different for different firmware, but I tried a few with the same > > result. > > >>> > > >>> Tomas > > >>> > > >>> On Mar 7, 2018 9:13 AM, "wes" <p...@the-wes.com> wrote: > > >>> > > >>> that's only if you want to generate a certain size. otherwise it just > > keeps > > >>> going until it runs out of blocks to fill. > > >>> > > >>> -wes > > >>> > > >>> On Tue, Mar 6, 2018 at 5:08 PM, Tim Garton <garton....@gmail.com> > > wrote: > > >>> > > >>> > Don't you need a "count=#" option to dd as well? Not at a computer > > right > > >>> > now otherwise I'd be able to check if that's the case... > > >>> > > > >>> > On Mar 6, 2018 5:02 PM, "Richard England" <rlengl...@frontier.com> > > >>> wrote: > > >>> > > > >>> > > On 03/06/2018 04:20 PM, Tomas Kuchta wrote: > > >>> > > > > >>> > >> Try to delete the original files first. Then create empty file > > using > > >>> > >> /dev/zero and copy it to the card. I bet that it will be there > on > > the > > >>> > card > > >>> > >> and some of your original data will disappear as result. > > >>> > >> > > >>> > >> My guess is that the card controller is deduplicating your > > /dev/zero > > >>> > >> blocks > > >>> > >> trying to protect the card from writes. > > >>> > >> > > >>> > >> Tomas > > >>> > >> > > >>> > >> On Mar 6, 2018 7:09 PM, "Russell Senior" < > > russ...@personaltelco.net> > > >>> > >> wrote: > > >>> > >> > > >>> > >> On Tue, Mar 6, 2018 at 3:04 AM, Russell Senior > > >>> > >>> <russ...@personaltelco.net> wrote: > > >>> > >>> > > >>> > >>>> On Tue, Mar 6, 2018 at 3:01 AM, Jim Karlock < > > jjkarl...@gmail.com> > > >>> > >>>> wrote: > > >>> > >>>> > > >>> > >>>>> My initial attempt to google this was unsuccessful (most > people > > >>> point > > >>> > >>>>>> out the write protect tab, not my problem). > > >>> > >>>>>> > > >>> > >>>>> > > >>> > >>>>> Bad switch on the write protect tab? (The tab operates a tiny > > >>> > switch.) > > >>> > >>>>> > > >>> > >>>> Nope. > > >>> > >>>> > > >>> > >>>> I can turn the switch to lock and it mounts the device read > only > > >>> very > > >>> > >>>> clearly. The behavior I observe is that it happily writes > > /dev/zero > > >>> > >>>> over the block device, but then when I read again, the old > data > > is > > >>> > >>>> still present. > > >>> > >>>> > > >>> > >>> For example, if I flip the tab to write protect tab to "Lock", > I > > get > > >>> > >>> this: > > >>> > >>> > > >>> > >>> # dd if=/dev/zero of=/dev/sdc status=progress bs=1M > > >>> > >>> dd: failed to open '/dev/sdc': Read-only file system > > >>> > >>> _______________________________________________ > > >>> > >>> PLUG mailing list > > >>> > >>> PLUG@pdxlinux.org > > >>> > >>> http://lists.pdxlinux.org/mailman/listinfo/plug > > >>> > >>> > > >>> > >>> _______________________________________________ > > >>> > >> PLUG mailing list > > >>> > >> PLUG@pdxlinux.org > > >>> > >> http://lists.pdxlinux.org/mailman/listinfo/plug > > >>> > >> > > >>> > > > > >>> > > |Perhaps using dd if=/dev/urandom |of=/dev/sdc status=progress > > bs=1M > > >>> > > ...just a thought. > > >>> > > > > >>> > > _______________________________________________ > > >>> > > PLUG mailing list > > >>> > > PLUG@pdxlinux.org > > >>> > > http://lists.pdxlinux.org/mailman/listinfo/plug > > >>> > > > > >>> > _______________________________________________ > > >>> > PLUG mailing list > > >>> > PLUG@pdxlinux.org > > >>> > http://lists.pdxlinux.org/mailman/listinfo/plug > > >>> > > > >>> _______________________________________________ > > >>> PLUG mailing list > > >>> PLUG@pdxlinux.org > > >>> http://lists.pdxlinux.org/mailman/listinfo/plug > > >>> > > >>> > > >>> > > >> _______________________________________________ > > >> PLUG mailing list > > >> PLUG@pdxlinux.org > > >> http://lists.pdxlinux.org/mailman/listinfo/plug > > > _______________________________________________ > PLUG mailing list > PLUG@pdxlinux.org > http://lists.pdxlinux.org/mailman/listinfo/plug > _______________________________________________ PLUG mailing list PLUG@pdxlinux.org http://lists.pdxlinux.org/mailman/listinfo/plug
