My best guess is it was formatted by a witch?
September 25, 2010 7:53 PM Subscribe
I've come across an unusual USB flash memory stick. What's going on here?
The drive was distributed free by a local car dealership. When the drive is plugged into a computer, two devices are detected. One is a standard removable drive with about 1Gb of memory. The other is an external CD-rom drive, which contains promotional information for the dealership.
This is true both under Windows and Linux. The device has so far resisted my efforts to stop it thinking it's a CD-rom as well as a flash drive, i.e. to convert it into a "normal" flash drive. I'm basically just curious. How was this done?
The drive was distributed free by a local car dealership. When the drive is plugged into a computer, two devices are detected. One is a standard removable drive with about 1Gb of memory. The other is an external CD-rom drive, which contains promotional information for the dealership.
This is true both under Windows and Linux. The device has so far resisted my efforts to stop it thinking it's a CD-rom as well as a flash drive, i.e. to convert it into a "normal" flash drive. I'm basically just curious. How was this done?
Response by poster: Hmm. The tool linked to from the Wikipedia page didn't seem to like it. The project team did note it was very alpha though, so I guess that's not unexpected. I may hack around with the source and see if I can make it happen. I do think you're right, aberrant. Thanks for the pointer.
posted by chmmr at 8:22 PM on September 25, 2010
posted by chmmr at 8:22 PM on September 25, 2010
It's a feature of the flash drive's controller chip. When the computer talks to the flash drive over USB, the drive can present itself as anything it wants, which in this case means something like a hub with both a mass storage device and a CD-ROM drive. The manufacturer probably has a special tool to enable/disable this mode.
Out of curiosity, since you said you have a Linux box, what's the output of the
posted by teraflop at 8:22 PM on September 25, 2010
Out of curiosity, since you said you have a Linux box, what's the output of the
lsusb command with this thing plugged in?posted by teraflop at 8:22 PM on September 25, 2010
Response by poster: teraflop, the relevant line from lsusb is:
Bus 001 Device 005: ID 058f:6387 Alcor Micro Corp. Transcend JetFlash Flash Drive
posted by chmmr at 8:25 PM on September 25, 2010
Bus 001 Device 005: ID 058f:6387 Alcor Micro Corp. Transcend JetFlash Flash Drive
posted by chmmr at 8:25 PM on September 25, 2010
Response by poster: Here's dmesg, just for the sake of interest:
[ 2447.461072] scsi 4:0:0:0: Direct-Access Generic Flash Disk 8.01 PQ: 0 ANSI: 2
[ 2447.461682] scsi 4:0:0:1: CD-ROM Generic Autorun Disk 8.00 PQ: 0 ANSI: 2
[ 2447.504785] sd 4:0:0:0: [sdc] 2030266 512-byte hardware sectors: (1.03 GB/991 MiB)
[ 2447.511411] sd 4:0:0:0: [sdc] Write Protect is off
[ 2447.511420] sd 4:0:0:0: [sdc] Mode Sense: 03 00 00 00
[ 2447.511425] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[ 2447.514422] sd 4:0:0:0: [sdc] 2030266 512-byte hardware sectors: (1.03 GB/991 MiB)
[ 2447.514912] sd 4:0:0:0: [sdc] Write Protect is off
[ 2447.514920] sd 4:0:0:0: [sdc] Mode Sense: 03 00 00 00
[ 2447.514925] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[ 2447.514935] sdc: sdc1
[ 2447.815199] sd 4:0:0:0: [sdc] Attached SCSI removable disk
[ 2447.815330] sd 4:0:0:0: Attached scsi generic sg2 type 0
[ 2447.818914] sr0: scsi3-mmc drive: 0x/0x caddy
[ 2447.819105] sr 4:0:0:1: Attached scsi CD-ROM sr0
[ 2447.819236] sr 4:0:0:1: Attached scsi generic sg3 type 5
posted by chmmr at 8:27 PM on September 25, 2010
[ 2447.461072] scsi 4:0:0:0: Direct-Access Generic Flash Disk 8.01 PQ: 0 ANSI: 2
[ 2447.461682] scsi 4:0:0:1: CD-ROM Generic Autorun Disk 8.00 PQ: 0 ANSI: 2
[ 2447.504785] sd 4:0:0:0: [sdc] 2030266 512-byte hardware sectors: (1.03 GB/991 MiB)
[ 2447.511411] sd 4:0:0:0: [sdc] Write Protect is off
[ 2447.511420] sd 4:0:0:0: [sdc] Mode Sense: 03 00 00 00
[ 2447.511425] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[ 2447.514422] sd 4:0:0:0: [sdc] 2030266 512-byte hardware sectors: (1.03 GB/991 MiB)
[ 2447.514912] sd 4:0:0:0: [sdc] Write Protect is off
[ 2447.514920] sd 4:0:0:0: [sdc] Mode Sense: 03 00 00 00
[ 2447.514925] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[ 2447.514935] sdc: sdc1
[ 2447.815199] sd 4:0:0:0: [sdc] Attached SCSI removable disk
[ 2447.815330] sd 4:0:0:0: Attached scsi generic sg2 type 0
[ 2447.818914] sr0: scsi3-mmc drive: 0x/0x caddy
[ 2447.819105] sr 4:0:0:1: Attached scsi CD-ROM sr0
[ 2447.819236] sr 4:0:0:1: Attached scsi generic sg3 type 5
posted by chmmr at 8:27 PM on September 25, 2010
If you just want to make the fake CDROM go away you could try something like (as root): echo 1 >/sys/bus/scsi/devices/4:0:0:1/delete
posted by Rhomboid at 11:29 PM on September 25, 2010 [1 favorite]
posted by Rhomboid at 11:29 PM on September 25, 2010 [1 favorite]
Hmm. The tool linked to from the Wikipedia page didn't seem to like it. The project team did note it was very alpha though, so I guess that's not unexpected.
Did you try the "official" uninstaller?
posted by madajb at 11:51 PM on September 25, 2010
Did you try the "official" uninstaller?
posted by madajb at 11:51 PM on September 25, 2010
On Sandisk-manufactured U3 flash drives (not always clearly labelled), it is possible to completely eliminate the U3 functionality in software. On off brands it may just be impossible. It's not a normal partition and standard partition editors won't work at all.
posted by miyabo at 2:32 AM on September 26, 2010
posted by miyabo at 2:32 AM on September 26, 2010
Many of the Western Digital external hard drives are also configured in this manner. It could be useful when using it on a netbook (without an optical drive) and trying to install software that insists on being installed via a CD.
posted by megatherium at 6:44 AM on September 26, 2010
posted by megatherium at 6:44 AM on September 26, 2010
It's a feature of the flash drive's controller chip. When the computer talks to the flash drive over USB, the drive can present itself as anything it wants, which in this case means something like a hub with both a mass storage device and a CD-ROM drive.
Kinda, although it's at a lower level than a hub. The drive is one mass storage device, but with two logical units -- one of which is a generic block device (the Flash drive part) and one of which is a fake CD-ROM drive.
(USB mass storage is basically SCSI commands wrapped in USB transactions, and part of that is the concept of the logical unit; most devices present only a single LUN, but some oddballs like this one have several.)
It's not a normal partition and standard partition editors won't work at all.
Right, it's in the flash drive's hardware, or at least in the flash drive's firmware.
I would suspect it's not a Sandisk U3 unit -- promo drives tend to be the cheapest off-brand lots available.
posted by We had a deal, Kyle at 11:15 AM on September 26, 2010
Kinda, although it's at a lower level than a hub. The drive is one mass storage device, but with two logical units -- one of which is a generic block device (the Flash drive part) and one of which is a fake CD-ROM drive.
(USB mass storage is basically SCSI commands wrapped in USB transactions, and part of that is the concept of the logical unit; most devices present only a single LUN, but some oddballs like this one have several.)
It's not a normal partition and standard partition editors won't work at all.
Right, it's in the flash drive's hardware, or at least in the flash drive's firmware.
I would suspect it's not a Sandisk U3 unit -- promo drives tend to be the cheapest off-brand lots available.
posted by We had a deal, Kyle at 11:15 AM on September 26, 2010
This thread is closed to new comments.
posted by aberrant at 7:55 PM on September 25, 2010