[lug] FAT32 USB drive

[Davide Del Vento]

The problem was the partition table.
Linux happily honored that and used the first (and sole) primary partition.
Android and the piano ignored that and considered the whole device a single
partition.
Once I deleted the partition table, Linux agreed with the others

On Sun, May 17, 2020 at 7:24 AM D. Stimits <stimits at comcast.net> wrote:

> I see two possibilities. One is that the signal quality prevents some
> devices from reading this. This can happen more than people think, but it
> is still somewhat rare and not likely (if you have a long cable then this
> becomes more likely).
>
> One thing many people do not realize is just how many options there are to
> various filesystem types. If you take a look at many of the modern
> distributions, specifically the file "/etc/mke2fs.conf", then you will find
> there are many optional parameters to the various variants of ext4. Older
> software may not handle all of the extensions, e.g., older 32-bit
> bootloaders will not recognize a valid ext4 filesystem if that filesystem
> has certain 64-bit extensions. In particular, older bootloaders on embedded
> systems tend to not find a filesystem at all if some of the 64-bit
> extensions are there, and this is true even though Linux itself can read
> this. The filesystem would be "missing" to anything not understanding those
> extensions.
>
> I do not know what extensions or options might be possible with
> VFAT/FAT32, so I couldn't tell you what to check for. I would think that
> the systems creating the format could probably read their own partitions
> from that format, but you might find another system does not even see the
> content any better than if the filesystem were totally corrupt beyond any
> ability to repair.
>
> On a system which cannot read the content you might try formatting again.
> Then copy the content back into the USB stick. My reason for saying to try
> this is that the system which cannot read a newer option will probably only
> create compatible formats. Older compatible formats can likely be read by
> the newer devices.
>
> On May 17, 2020 at 6:21 AM Davide Del Vento <davide.del.vento at gmail.com>
> wrote:
>
> Folks,
>
> I have a digital piano which can put stuff on USB devices (unspecified
> filesystem), so I formatted an USB drive to FAT32, put some stuff from the
> piano to it and tried to read them from my linux box.
>
> Funny enough, the drive showed empty in Linux, but the content was there
> when looking from the piano. I tried on a Mac which responded "The disk you
> inserted was not readable by this computer".
>
> So I tried Android. In fact I can see the digital piano files via Android
> (yay!)
>
> Funny thing, if I create files and directories on that USB drive from
> Linux, none of them shows up in Android.
>
> So it looks like this USB drive has two lives: one which is visible only
> from Linux, and the other which is visible from the digital piano and
> Android.
>
> Am I still sleeping and having a bad dream? Simple Googling did not reveal
> anything obvious....
>
> Thanks for any clues!
> Davide
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