usb drive connects as different devices when connecting to my computer

okos · 09-13-2008, 10:38 PM

I have a 1 tb usb drive. So far I have three, 200gb partitions and the rest unused. I wanted to setup the usb drive so that only I can use it and in my home directory. However when I connect the usb drive at boot or when my computer is already running, the partitions show up as different devices. At boot the partitions are /dev/sda1 ,2,3 . When I plug the usb drive in after my computer is running, I get /dev/sdb or something similar. I also get a different mount point such as /media/disk-1 instead of /home/me/...
Further more, I can only mount as root instead of me when the device is different.

I set my fstab to look as so:

Code:

/dev/hdc2        swap             swap        defaults         0   0
/dev/hdc1        /                ext3        defaults         1   1
/dev/hdc3        /vm              ext3        defaults         1   2
#/dev/cdrom      /mnt/cdrom       auto        noauto,owner,ro  0   0
#/dev/fd0         /mnt/floppy      auto        noauto,owner     0   0
devpts           /dev/pts         devpts      gid=5,mode=620   0   0
proc             /proc            proc        defaults         0   0
tmpfs            /dev/shm         tmpfs       defaults         0   0
/dev/sda1       /home/me/mybook vfat    rw,auto,uid=1000,sync,exec        0      0
/dev/sda2       /home/me/backup ext3    rw,auto,uid=1000,sync,exec      0      0
/dev/sda5       /home/me/windblows vfat   rw,auto,uid=1000,sync,exec      0      0

Is this a udev issue? How can I mount as the same device and mount point each time?

Vincent_Vega · 09-13-2008, 10:43 PM

You'll have to create a new udev rules file. It's a somewhat lengthy process, but not very complex. Google it - you'll find a couple clear tutorials that will help you do it. It's time well spent.

Vincent_Vega · 09-13-2008, 10:44 PM

This is the one I used. Worked perfectly for me.

http://www.reactivated.net/writing_udev_rules.html

T3slider · 09-13-2008, 11:27 PM

You can specify a device by its UUID in /etc/fstab (read `man fstab`). This should allow the drive to be mounted properly and always in the same location through fstab.

masonm · 09-14-2008, 09:35 AM

Quote:

Originally Posted by T3slider

You can specify a device by its UUID in /etc/fstab (read `man fstab`). This should allow the drive to be mounted properly and always in the same location through fstab.

That's the way I would go, and it's much quicker than writing udev rules LOL

Vincent_Vega · 09-14-2008, 07:15 PM

Can you use that method for a single drive that is partitioned? I'm not familiar with the UUID way - I'll look into it - but I know the udev rules method is capable of dealing with any scenario.

okos · 09-14-2008, 07:35 PM

Quote:

Originally Posted by masonm

That's the way I would go, and it's much quicker than writing udev rules LOL

I started reading the udev link last night before I fell asleep

How do you do it the uuid way?
What is uuid anyways?

Vincent_Vega · 09-14-2008, 07:43 PM

I'm not sure this UUID is what you're looking for and here's why: You're trying to assign a piece of hardware to a certain device in the /dev directory. The fstab will be easy for assigning /dev/sda1 to a specific mount point, but who's to say /dev/sda1 is always the same piece of hardware?? I would love to see an example of using UUID to identify a specific piece of hardware, assign it to the proper /dev item and then mount it to a specific mount point.
With udev rules, I can make sure the media reader in my printer is always mounted to a specific directory; I can ensure that all four of my jump drives get mounted in the same exact place every time I plug them in, regardless of what order I plug them in.
I'm not saying UUID can't do it - I just want to see *how* it does it. So please give an example.

Vincent_Vega · 09-14-2008, 07:46 PM

Okos, what are you trying to map? Tell me what piece(s) of hardware you're trying to set up and I'll tell you exactly how to do it. Then you'll see that udev rules aren't hard at all! It just takes about 2-3 minutes for each piece of hardware but once it's done, you can copy that rules file to any linux box and it'll work exactly the way you want, as long as you create the custom mount point directories, because each piece of hardware has a unique identifying number that udev will use to make all of this happen.

Vincent_Vega · 09-14-2008, 07:50 PM

Here it is - a UUID How-To. Looks like it works just like the udev rules I guess. You can give it a shot and tell us how everything goes.

http://linux.byexamples.com/archives...tab-with-uuid/

Vincent_Vega · 09-14-2008, 07:58 PM

I used this command:

Code:

blkid /dev/sdd1

to get a simple UUID. Then I added it to my /etc/fstab:

Code:

UUID=C123-C567  /media/jumpdrive1  vfat  defaults  0  0

Then I created the /media/jumpdrive1 directory and mounted it perfectly.

I'm really happy about this thread! I learned something very useful. Contrary to what I thought this method wouldn't do, it basically just forgets the entire /dev designation and identifies hardware with UUID. Although each piece of hardware might change the /dev item is gets assigned, the mounting of that hardware is not affected.

T3slider · 09-14-2008, 08:52 PM

Interesting self-discussion (

) and thanks for providing a full solution. I should learn to write udev rules for other reasons, but for something like this fstab seems like the easier solution.

Vincent_Vega · 09-14-2008, 08:58 PM

LOL! Well, I think there's nothing worse than someone getting help here and never sharing the final solution they find. I figured that I would just go ahead and talk to myself for a while, and at the same time give the solution since I was just as interested in this issue as anyone. It should be noted, however, that I generally don't have these self-discussions...

okos · 09-14-2008, 10:46 PM

I will try the uuid and read the link.
Thanks guys for all of your help!
I will follow up after I make the changes.

BTW Talking to yourself is therapeutic.

Just don't answer or they will throw you in the funny farm.

One last thing Vincent, which Arnold is #1? Are you talking about the CA govenor?

Vincent_Vega · 09-14-2008, 10:54 PM

That's who I'm referring to! That is what was on the front of the t-shirt he wore at the end of the great documentary "Pumping Iron" when he won the 1975 Mr. Olympia. It's a must-see. The guy is a legend. There's no denying that!!