[SOLVED] Need advice on using UUID to idetify usbstick rootdrives

rusma · 06-06-2010, 07:10 AM

Hi

I'm currently configuring my nslu2 to reboot correctly, having the Debian Lenny Operating System split over two usbsticks - this is quite difficult, i think.

You see, sometimes it boot, sometimes not. Therefore, I've decided to try UUID naming instead of the default sdX naming system. Maybe udev naming too ... dunno.

Here some person says it is important to do one usb stick at a time. How important is this(?) when I have the OS split over two usb-sticks, not just one?

I have not really used udev for other than renaming ethernet and wlan devices; so some tips on using it for renaming usb-devices would be nice. Is renaming on the grounds of UUIDs the most sensible way, you think?

I have set up the cabling to the nslu2 like this:

PHP Code:



   lenny.localnet 
   | 
 (eth0) 
   | 
[NSLU2 (Debian Lenny)]---(usb)---[SANDISK 8GB stick (normal writing rate)] 
   | 
 (usb) 
   | 
[USB HUB]---(usb)---[veeeery large and sleepy external harddrive] 
   | 
 (usb) 
   | 
[CORSAIR 4G stick (superfast writing rate)]

/boot, /home, /usr/local and /var/log is on the Sandisk, and /, /tmp, /usr and /var/log is on the Corsair. Is this a good structure? Now, installing packages is damn slow (then it's using the Sandisk), but doing simple editing in Vim and logging in from ssh is like to an ordinary machine with the OS on a harddrive. This is not that bad, since I'm doing editing in Vim more often that installing packages (maybe just once).

Hmm ... quite a few questions here ...

All answers appreciated.

Edit: [SOLVED], just go on with naming by UUID if you boot from several memorysticks. Maybe it is preferable to rebuild the initramfs for each edit to the fstab file ...

Robhogg · 06-06-2010, 08:59 AM

You don't need to rename a device to get the UUID. You can get the device's existing UUID with either the vol_id utility, or dumpe2fs (for extn filesystems).

I routinely use UUIDs in /etc/fstab for USB drives (though mainly so that removable drives mount in predictable locations).

rusma · 06-06-2010, 11:29 AM

Quote:

Originally Posted by Robhogg

I routinely use UUIDs in /etc/fstab for USB drives (though mainly so that removable drives mount in predictable locations).

A predicable location is precisely what I am looking for.

What happens during boot if I use only the UUIDs of the partitions of (for example) the SANDISK, and leave the Corsair as it is (sdbn)?
Will they still be named sda snd sdb during every boot?
How will the names of the drives in the output of df look?

rusma · 06-08-2010, 06:59 AM

OK. Seems like it all worked as planned/guessed of at first. Booting from the USB hub does not make any difference now with all the right UUIDs in place. Booting from the USBhub is also preferrable I think, so the NSLU2 card does not have to handle as much throughput and power (it is all handeled to a certain degree by the USB hub).

It seems Squeeze will handle all the UUID values by default.

OT: I have also managed to print a testpage from by Deskjet using hplip