Curious case of read-only flash drive

[Petter Adsen]

On Fri, 20 Nov 2015 20:10:36 -0800
MR ZenWiz <mrzenwiz at gmail.com> wrote:

> On Fri, Nov 20, 2015 at 12:25 AM, Petter Adsen <petter at synth.no>
> wrote:
> >
> > What kernel messages do you get when you insert the drive?
> >
> > Run 'dmesg -w' in a terminal, insert the drive, and post the lines
> > it adds.
> >  
> Well, dmesg -w says that's not a valid option.

Must be an older version. It just does the same as 'tail -f', so it's
not important.

> However, dmesg shows this:
> 
> [1892293.658683] usb 3-7: new high-speed USB device number 72 using
> xhci_hcd [1892293.676124] usb 3-7: New USB device found,
> idVendor=0930, idProduct=6545 [1892293.676133] usb 3-7: New USB
> device strings: Mfr=1, Product=2, SerialNumber=3
> [1892293.676138] usb 3-7: Product: TransMemory-Mx
> [1892293.676142] usb 3-7: Manufacturer: TOSHIBA
> [1892293.676146] usb 3-7: SerialNumber: FFFFFFFFFFFFEE11200053D9
> [1892293.676831] usb-storage 3-7:1.0: USB Mass Storage device detected
> [1892293.677153] scsi67 : usb-storage 3-7:1.0
> [1892294.675124] scsi 67:0:0:0: Direct-Access     TOSHIBA
> TransMemory-Mx   PMAP PQ: 0 ANSI: 6
> [1892294.675776] sd 67:0:0:0: Attached scsi generic sg7 type 0
> [1892294.675948] sd 67:0:0:0: [sdf] 121858560 512-byte logical blocks:
> (62.3 GB/58.1 GiB)
> [1892294.676358] sd 67:0:0:0: [sdf] Write Protect is off
> [1892294.676367] sd 67:0:0:0: [sdf] Mode Sense: 45 00 00 00
> [1892294.676701] sd 67:0:0:0: [sdf] Write cache: disabled, read cache:
> enabled, doesn't support DPO or FUA
> [1892294.977043]  sdf: sdf1
> [1892294.978090] sd 67:0:0:0: [sdf] Write Protect is on
> [1892294.978098] sd 67:0:0:0: [sdf] Mode Sense: 45 00 80 00
> [1892294.978412] sd 67:0:0:0: [sdf] Attached SCSI removable disk
> 
> Not sure what all that means, except it seems clear that the write
> protect gets turned on during the mounting process, so I'm hoping
> there's a way to turn it back off...

No, this happens before the drive gets mounted, these are just messages
from the kernel detecting the drive. I have no idea why it sees the
drive first as writable and then read-only, my guess would be that the
drive is borked.

I assume the drive behaves similarly no matter what port or machine you
plug it in to?

Also, take a look at this:

http://superuser.com/questions/402688/why-did-my-flash-drive-become-read-only-and-how-can-i-fix-it?rq=1

There are some suggestions there, the top rated answer mentions a tool
you can try, but of course you need to be careful with binaries from
untrusted sources. The manufacturer of the drive might have something
similar, contact them.

Petter

-- 
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"Are you sure?"
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