fdisk finds usb drive only every 4th attempt -- very strange

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fdisk finds usb drive only every 4th attempt -- very strange

Postby tilman victor on Mon Oct 01, 2012 7:23 am

Got 2 of those very tiny delock 8GB "nano" memory sticks.
They are detected immediately every time I plug them in ("sd [increasingnumber]:0:0:0...")
but fdisk -l doesn't show them.
2nd attempt: no.
3rd: no
4th: /dev/sdc: 7948 MByte, (...)
5th: no
(...)
8th: /dev/sdc: 7948 MByte, (...)
and so on.

Despite this, it's always possible to MOUNT the drive,
although this takes a little while every time fdisk hasn't found it.
Once mounted, fdisk shows the drive, too.
After umount, fdisk needs 4 attempts again.

What's going on here???

OH YES, AND:
My main intention is (was?) to boot from them.
Still a good idea?
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Re: fdisk finds usb drive only every 4th attempt -- very str

Postby DrHu on Mon Oct 01, 2012 11:49 am

In a terminal..
Code: Select all
sudo fdisk -l

--you need that to see the output

If you use that method and still have a problem detecting the drive data, I would suggest cleaning up the file system that is installed on those drives, it is usually FAT, not ntfs..
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Re: fdisk finds usb drive only every 4th attempt -- very str

Postby tilman victor on Tue Oct 02, 2012 4:05 am

No - mounting and accessing the data ALWAYS works (one single partition on each stick, one FAT32, ext2 the other)
and once mounted, the device is listed by fdisk. Always. Period.

But after umount, fdisk seems to prefer deciding itself whether/when to show it.

So here we have two drives that only reliably exist if someone (mount in this case) is looking.
Quantum-based memory.
No doubt.
That's why these gadgets are so small...
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fdisk finds usb drive only every 4th attempt -- UPDATE

Postby tilman victor on Fri Oct 05, 2012 4:03 am

UPDATE: (a bit differnt from what I posted earlier---as of now, I don't know why)

Immediately after mounting, I can read from the device. Even big files.
But after being idle for a few seconds (or, as I suspect, one "fdisk -l" too much) the device vanishes.
df thinks it's still mounted, but I only get read errors.
umount complains: "previous I/O-error to superblock detected".

Additionally, "fdisk -l (that device)" causes any file transfer from it to stop immediately with an I/O-error.

What's going on and how can I stop it?
Any hyperactive daemon at work?

just in case it matters:
I know that some flash drives identify themselves as card readers.
This one is listed by lsusb as "ID 14cd:8123 Super Top SD MMC Reader"
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Re: fdisk finds usb drive only every 4th attempt -- very str

Postby mensfort on Sun Oct 14, 2012 9:05 am

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