USB Flash Drive

awj78 · 01-30-2006, 10:17 PM

I'm trying to use a lexar media usb jumpdrive on Slackware, but when I try to mount it (with mount usbfs), I get

mount: according to mtab, usbfs is already mounted on /proc/bus/usb

What's the deal?

patrokov · 01-31-2006, 12:13 AM

You need to mount it using vfat, not usbfs. Also, on some flash drives, the manufacturer uses some bizarre partitioning scheme that Linux can't recognize. In order to get my SanDisk Cruzer working, I had to delete the partition table, create a new one, and then reformat. (I think the non-standard formatting is part of their "security feature".)

nitinatindore · 01-31-2006, 12:20 AM

you dont have to mount usbfs,
you have to mount the device to a mount point see "man mount"

Unless you have usb hard disks or otherwise Thumb drive partition is usually /dev/sda1 so you have to mount it as:

#mount /dev/sda1 /mnt/USB
You may replace /mnt/USB with any locations you like.
btw. modern mount usually takes care of filesystem itself,so you dont have to specify it specifically.

awj78 · 01-31-2006, 12:21 AM

How do you know where the drive is located (/dev/sda1)? Just guess?

duffmckagan · 01-31-2006, 04:40 AM

Quote:

Originally Posted by awj78

How do you know where the drive is located (/dev/sda1)? Just guess?

Its not just guessing.

USB Flash drives are SATA devices.

Now here, you must know what is SATA and what iS IDE.
Heard of /dev/hda, /dev/hdb?

hda -- this h is for IDE devices.

sda -- this s is for SATA devices.

So, if you don't have any SATA devices attached to your computer (other than your FLash drive) -- like a SATA Hard Drive or CDROM, you will find your Flash Drive under /dev/sda. Otherwise, you may find it under /dev/sdb or /dev/sdc.
/dev/sda1 (this 1 represents the partition number.)

To view more details about your Flash drive, you can run

Code:

$fdisk -l /dev/sda

This is the simplest explanation I can give.

awj78 · 01-31-2006, 09:03 AM

Thanks for all your help!

michaelk · 01-31-2006, 12:59 PM

Just a minor clarification.
sdx -- The s is for SCSI not SATA.

USB, Firewire and SATA drives are all configured like SCSI devices and thus will have a device ID of /dev/sdx.

SCSI device IDs are typically assigned automatically, i.e. the first drive on the first controller will be sda. The next sdb and so on. If you do not have any other SCSI like devices then indeed it will be sda.

duffmckagan · 01-31-2006, 01:18 PM

Aah...sorry.

Thats what I meant :P

For a while, I forgot that SATA is related to HDDs. :P

patrokov · 01-31-2006, 11:44 PM

Which also means that if you don't have scsi support and emulation enabled or loaded as a module, you'll never be able to mount your usb key. Not usually a problem with standard kernels, but if you compile your own, make sure you put it in there.

Interesting trivia: if you pull your usb key out without mounting it, the next time you plug it in, it will not be /dev/sda, but /dev/sdb. If you plug more than one in, they will be successive letters. And finally, if you have any SATA drives, they also get assigned preferentially to the lower letters. So instead of using fdisk -l /dev/sda, it's better to use something like "fdisk -l | grep FAT16" (as most USB keys are formatted with FAT16 to be compatible with Windows).

arilect · 02-02-2006, 11:14 AM

Quote:

Originally Posted by patrokov

Interesting trivia: if you pull your usb key out without mounting it, the next time you plug it in, it will not be /dev/sda, but /dev/sdb. If you plug more than one in, they will be successive letters. And finally, if you have any SATA drives, they also get assigned preferentially to the lower letters. So instead of using fdisk -l /dev/sda, it's better to use something like "fdisk -l | grep FAT16" (as most USB keys are formatted with FAT16 to be compatible with Windows).

I think udev and rules could help to solve the problem. See this article http://www.linuxjournal.com/article/7316.