how do i mount a usb cdrom?

slinky2004 · 01-28-2006, 02:56 PM

i have a usb cdrom drive that i've been using with windows, but i want to use it to read a cd on my linux computer. i expected it to show up as scsi device sda because my flash drive and usb hard drive show up as sda1. when i plug it in, i see some entries in dmesg that looks like it has been recognized, but i dont know what device its assigned to, dmesg mentions sr0 and sg0, but i cant mount either of those. i have scsi cdrom support compiled into my kernel so i should be able to do this. can anybody tell me how to mount this thing?

Nylex · 01-28-2006, 03:03 PM

Post the exact output of dmesg please and also, what happens when you do try to mount /dev/sr0 for example?

Edit: Just to say, my USB CD-RW drive gets attached to /dev/sr0.

Brian1 · 01-28-2006, 03:16 PM

Normally it would be /dev/scd0 for a cdrom.

A line in /etc/fstab like this.

Code:

/dev/scd0		/mnt/cdrom2             auto    noauto,owner,rw 0 0

Which of course mounts to the directroy /mnt/cdrom2.
Brian1

slinky2004 · 01-28-2006, 09:34 PM

/dev/scd0 works, but i dont understand how i could have found that out. in the past, when i plug in a usb device such as a jump drive or hard drive, dmesg or /var/log/messages will say it's mounted as sda1, etc. and i'll access it that way. nothing ever told me this drive was at /dev/scd0. as i said, dmesg said that it was at either sr0 or sg0. sr0 apparently didn't exist and sg0 wasn't a block device.
here is the output of dmesg after i plug it in:

Quote:

usb 1-3: new high speed USB device using ehci_hcd and address 3
scsi0 : SCSI emulation for USB Mass Storage devices
HID device not claimed by input or hiddev
usb-storage: device found at 3
usb-storage: waiting for device to settle before scanning
Vendor: Model: RW-241040 Rev: 1.02
Type: CD-ROM ANSI SCSI revision: 00
sr0: scsi3-mmc drive: 40x/40x writer cd/rw xa/form2 cdda tray
Attached scsi CD-ROM sr0 at scsi0, channel 0, id 0, lun 0
Attached scsi generic sg0 at scsi0, channel 0, id 0, lun 0, type 5
usb-storage: device scan complete

bump

Brian1 · 01-29-2006, 10:02 AM

I don't know exactly what is going on, but USB uses the kernel scsi interface to save on a lot of new code to write for USB to be used in the kernel. All scsi cd-dvd-optical drives use the /dev/scd* naming. sr0 and sg0 are low level scsi block devices. Once the kernel understands the device it then remaps it to /dev/sd* or /dev/scd* depending on the interface code. These is a very crud info. I am sure there are others know the details of it. If you install the sg-utils and run some of the commands then some of it will make sense.

Brian1