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Re: Debian Live USB fails; bricks the USB stick




Hi,

Felix Miata wrote:
> Don't we know it was a GPT disk to start with? If no iso ever got a chance to
> finish writing all the way out to end of disk, the backup/reserve/secondary
> partitioning at end of disk would still report a "filesystem" exists,

The backup GPT of the old stick content could indeed have the read-only
bit set in the flags word of the partition entry.
But that backup would first have to be activated by moving it to the
normal position of the GPT near the start of the drive.

In general the partition table should not keep dd from writing to the
device file of the whole drive.
Further it was possible to put the ISO onto the stick by help of dd,
when the main GPT would have been still present and valid.


> Also, why are this/these stick(s) getting flip-flopped between sdd and sdc?

That's because Kent plugged them in at the same time, i guess.
sdc is the clearly ill one, sdd is the one which is at least readable.


Kent West wrote:
> > > dd: failed to open '/dev/sdd': Read-only file system

i wrote:
> > Why does dd talk of filesystems ?

Henrique de Moraes Holschuh wrote:
> Because the only error number usable for "this thing is read-only" in
> POSIX is EROFS, so that's what a read-only block device reports.
> ...
> Anyway, if this is a pendrive or some other flash-based media, it most
> often means it is in the fail-safe last-resort mode (switched to
> read-only access so that you can try to salvage some data off it).

Valid theory. One can read this in the web about SanDisk devices.

But i am reluctant to declare two out of two USB sticks ill.
For now i still deem it possible that something like udev decided to
block access because of the data it saw on the device.

The decisive experiments would be to try writing to the sdd stick on
some other operating system with very different software between kernel
and userland. (Best would be an old GNU/Linux without any systemd/udev.)

Although i really do not believe in the theory that the ISO can kill
the USB stick, i leave the decision to Kent whether he wants to risk
a third stick (preferrably a young one) for experiments.


Have a nice day :)

Thomas