Unable to erase USB-stick. Mounts as read-only

tom4everitt · 12-01-2009, 11:17 AM

Hello,

I'm trying to dd an arch linux .img file onto my usb, but it won't let me do it. It tells me:

Code:

dd: opening `/dev/sdb': Read-only file system

I get the same error when I try to do any modifications to it in fdisk or gparted:

Code:

mount: block device /dev/sdb1 is write-protected, mounting read-only

When mounted I can't see any of the files on it. The file system is fat-something I believe (16 according to gparted).

The boot flag was set (by rEFIt I think). Perhaps that's causing the problem?

knudfl · 12-01-2009, 12:24 PM

dd if=<img> of=/devsda1

If it fails, suggest : format sda1 with gparted.
.....

EDIT EDIT : Better not do the above, ref. @jschiwal, post # 3.
.....

jschiwal · 12-01-2009, 12:38 PM

knudfl: Your post if typed correctly would cause the OP to erase his operating system.

jschiwal · 12-01-2009, 12:49 PM

Is the image for a hard drive filesystem, e.g. contains boot loader & partitions, or of a single partition.

What command did you use, and did you perform it as root. Normally the /dev/sdb device doesn't contain a file system. Is this a U3 drive? If so it may have a rom portion (or electronics that deny writes to the partition table) that presents itself as a CDROM device.

From a Wikipedia entry:

Quote:

Originally Posted by http://en.wikipedia.org/wiki/U3#APIs

Removal

Reformatting the drive will remove some of the software, but not all of it. The virtual CD-ROM drive cannot be removed by reformatting because it is presented to the host system as a physical device attached to a USB hub[6]; the official U3 Launchpad Removal Software, available on the manufacturer's website, disables the virtual CD drive device, leaving only the USB mass storage device active on the U3 USB hub controller, at which point the remaining software is removed by a subsequent format, performed by the removal software itself.

tom4everitt · 12-01-2009, 01:09 PM

Quote:

Originally Posted by jschiwal

Is the image for a hard drive filesystem, e.g. contains boot loader & partitions, or of a single partition.

What command did you use, and did you perform it as root. Normally the /dev/sdb device doesn't contain a file system. Is this a U3 drive? If so it may have a rom portion (or electronics that deny writes to the partition table) that presents itself as a CDROM device.

From a Wikipedia entry:

Well, the image is supposed to go to /dev/sdb (rather than /dev/sdb1) according to the page from which it is downloaded.

I performed it as root, the command was

dd if=imagename.img of=/dev/sdb

How would I know if it's a U3 drive? It seems to contain a file system, there is a /dev/sdb1 partition on it at least. It presents itself as a usb flash drive.

jschiwal · 12-01-2009, 02:07 PM

Quote:

Well, the image is supposed to go to /dev/sdb

Fine. That indicates that it is an image file for a disk. E.G. for /dev/sdb and not /dev/sdb1.
You can use "file imagefile.img" to check. That isn't the problem at hand. I just wanted to make certain that you had the right kind of image to proceed.

You could run "sudo tail -f /var/log/messages" and then plug in the device. That should tell you what the kernel knows about the device, which device it is, and how many devices are detected.

tom4everitt · 12-01-2009, 02:28 PM

Ooh, cool tips. Not that I managed to solve a lot from it but.

The tail command gave this output, couldn't extract much useful info from it (but i'm definitely gonna remember the command for another time):

Code:

Dec  1 21:18:00 macbookpro kernel: usb 1-1: new high speed USB device using ehci_hcd and address 10
Dec  1 21:18:00 macbookpro kernel: usb 1-1: New USB device found, idVendor=0204, idProduct=6025
Dec  1 21:18:00 macbookpro kernel: usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
Dec  1 21:18:00 macbookpro kernel: usb 1-1: configuration #1 chosen from 1 choice
Dec  1 21:18:00 macbookpro kernel: scsi7 : SCSI emulation for USB Mass Storage devices
Dec  1 21:18:05 macbookpro kernel: scsi 7:0:0:0: Direct-Access     ChipsBnk Flash Disk       2.00 PQ: 0 ANSI: 2
Dec  1 21:18:05 macbookpro kernel: sd 7:0:0:0: Attached scsi generic sg2 type 0
Dec  1 21:18:05 macbookpro kernel: sd 7:0:0:0: [sdb] 517375 512-byte hardware sectors: (264 MB/252 MiB)
Dec  1 21:18:05 macbookpro kernel: sd 7:0:0:0: [sdb] Write Protect is on
Dec  1 21:18:05 macbookpro kernel: sd 7:0:0:0: [sdb] Assuming drive cache: write through
Dec  1 21:18:05 macbookpro kernel: sd 7:0:0:0: [sdb] Assuming drive cache: write through
Dec  1 21:18:05 macbookpro kernel: sdb: sdb1
Dec  1 21:18:05 macbookpro kernel: sd 7:0:0:0: [sdb] Attached SCSI removable disk

fdisk found this, I don't know if it could be related at all.

Code:

Partition 1 has different physical/logical endings:
     phys=(1023, 15, 32) logical=(1010, 7, 31)
Partitions 1: cylinder 1024 greater than maximum 1010
Partition 1: previous sectors 517374 disagrees with total 524287
31 unallocated 512-byte sectors

jefro · 12-01-2009, 08:28 PM

Looks like we are trying to access it with a Mac OS.

See this. http://www.diamond-memory.com/Manual...AD%20GUIDE.pdf Seems to indicate a very odd flash drive.

business_kid · 12-02-2009, 03:28 AM

With respect to previous posters, Any time I had that problem (Read only) there was a small switch on the usb key which write protected it. That would get switched, and I would stop tearing my hair out. Does it have a switch? Switch it!

tom4everitt · 12-02-2009, 07:00 AM

Quote:

Originally Posted by business_kid

With respect to previous posters, Any time I had that problem (Read only) there was a small switch on the usb key which write protected it. That would get switched, and I would stop tearing my hair out. Does it have a switch? Switch it!

BRILLIANT! It wasn't harder than that :P Works perfectly now...

Thanks to everyone, and you especially!