[GTALUG] wierd usb problem: refuses to mount rw

[Matt Price]

In what appears to be a recent and spontaneous change, teh Ubuntu box I use
to run our PVR has stopped mounting USB keys rw.  THis is on Ubuntu -- when
Ifirst noticed the problem I was still running 13.10, but am now updated to
14.10.

WHen I plug in a key, it will sometimes (but not always!) appear to mount
as usul to /media/matt/something , opening up a nautilus window.  but any
attempt to write to the disk will fail due to lack of write permission.

Attempts to remount also fail:

~$ sudo mount -o rw,remount /media/matt/Linux\ Mint\ 17\ Xfce\ 32-bit/
mount: cannot remount /dev/sdb1 read-write, is write-protected


Meanwhile, dmesg says this, which I don't entirely understnad:

  794.736021] usb 1-6: new high-speed USB device number 4 using ehci-pci
[  794.869458] usb 1-6: New USB device found, idVendor=1221, idProduct=3234
[  794.869463] usb 1-6: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[  794.869466] usb 1-6: Product: Flash Disk
[  794.869469] usb 1-6: Manufacturer: USB2.0
[  794.869471] usb 1-6: SerialNumber: 100000000000068B
[  794.869731] usb-storage 1-6:1.0: USB Mass Storage device detected
[  794.872208] scsi7 : usb-storage 1-6:1.0
[  795.874368] scsi 7:0:0:0: Direct-Access     USB2.0   Flash Disk
2.50 PQ: 0 ANSI: 2
[  795.874586] sd 7:0:0:0: Attached scsi generic sg2 type 0
[  795.875227] sd 7:0:0:0: [sdb] 2068480 512-byte logical blocks: (1.05
GB/1010 MiB)
[  795.876225] sd 7:0:0:0: [sdb] Write Protect is off
[  795.876228] sd 7:0:0:0: [sdb] Mode Sense: 0b 00 00 08
[  795.877226] sd 7:0:0:0: [sdb] No Caching mode page found
[  795.877229] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[  795.882222] sd 7:0:0:0: [sdb] No Caching mode page found
[  795.882226] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[  795.882860]  sdb: sdb1
[  795.882863] sdb: p1 size 2445312 extends beyond EOD, enabling native
capacity
[  795.885227] sd 7:0:0:0: [sdb] No Caching mode page found
[  795.885229] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[  795.885858]  sdb: sdb1
[  795.885861] sdb: p1 size 2445312 extends beyond EOD, truncated
[  795.891228] sd 7:0:0:0: [sdb] No Caching mode page found
[  795.891233] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[  795.891235] sd 7:0:0:0: [sdb] Attached SCSI removable disk
[  796.069733] ISO 9660 Extensions: Microsoft Joliet Level 3
[  796.070732] ISO 9660 Extensions: RRIP_1991A

-----

this happens with all usb keys, all of which I am able to mount on my
laptop, which runs arch linux.

Any htoughts on how to proceed?

Thanks as always,
Matt
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