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Entries tagged "usb".

And if you fail gym, you'll never get into college.

14th November 2009

Today I rebooted my desktop for the first time in a few months. This did not go well. Probably as a result of this issue with lvm/dmsetup/cryptsetup conflicting my system didn't boot, and the error message was non-helpful.

The error shown just after grub2 had started to load a system was :

Cannot find LVM volume group gold-vol

The actual cause was that I was missing the mdadm package. D'oh. My desktop has 2x500Gb drives setup as:

 sda1 + sdb1 = md1  = /boot [1Gb]
 sda2 + sdb2 = md0  = LVM storage [460Gb]

(It's only as I write this that I'm surprised that md1 + md0 are opposite to the fashion I'd have expected them to be. I guess I just created them in the "wrong" order at install time. Oops)

So without mdadm the LVM volume group on /dev/md0 couldn't be found, and that in turn meant my root filesystem couldn't be accessed at /dev/gold-vol/root.

Fixing this was a real pain. Because the system is the PXE network host on my LAN I couldn't boot it that way, and the machine has no CD-ROM drive connected.

My solution was to download and install System Rescue CD, which I placed upon a USB stick. This worked beautifully once I realised I had to boot with rescue64 to get a 64-bit kernel capable of letting me run chroot.

Oddly enough I had problems booting from USB. If I powered down my system and hit the "on" switch the system just ignored the USB stick. I noticed that my USB mouse and card reader didn't show any power lights at all - not until after grub had failed to boot the system.

So the process of booting from USB was eventually determined to be:

  • Poweroff system.
  • Power on system - wait for grub to fail to boot kernel.
  • At this point the USB mouse and card reader would be initialised in some fashion and would show their LED lights.
  • Press Ctrl-alt-delete - at which point the BIOS would allow the USB booting to occur.

Very very odd. I guess its a question of what does the "USB enabling". I'd previously assumed the BIOS would do this setup - but looking over at another system I notice that the USB mouse doesn't "come alive" until mid-way through the Linux boot process even though I know that BIOS has options for "Enabling USB mouse & keyboard". Maybe I'm missing something obvious ..?

In conclusion .. I restarted GDM for the first time in weeks and rebooted, and this was a bad idea.

ObFilm: Never Been Kissed

Tags: computers:gold, mdadm, recovery, usb, usb booting. | 3 comments.

 

Did you feel it in your knees

10th May 2009

This post is being made from my EEEEEeeee PC, using a 3G modem plugged into the USB port. The fact that I'm sat on my sofa, within easy reach of both a network cable and multiple WiFi access points is irrelevant!

I started my adventure yesterday evening, getting pretty annoyed along the way that that it wasn't just plug and go. It turns out I was suffering from two problems:

  • The USB device itself alternates between being a modem and being a dumb USB storage device (full of Windows software).
  • My copy of Network-Manager was too old.

In short from my Lenny installation I had to upgrade to Sid to get a copy of Network Manager with a "Mobile Broadband" section in its preferences. (I looked for backports, to no avail, and I didn't have the patience to make one mysefl). The new connection looks like this:

Number*99#
Username[blank]
Passwordpassword
APNm-bb.o2.co.uk
PIN0000
PUK0000

Once I added the connection discovered the USB modem device (/dev/ttyUSB0) just didn't work - and I learned about the dual-nature of the device. Thankfully switching is nice and easy "apt-get install usb-modeswitch" then:

# disable storage
usb_modeswitch -v 12d1 -p 1003 -d 1
# enable modem
usb_modeswitch -v 12d1 -p 1003 -H 1

Once that was done the connection worked almost immediately. (I just had to upgrade to a 2.6.29 kernel because I got panics on the Lenny kernel; something the upgrade installed but I'd previously ignored. Kernels: Bane of my life.)

Update: I do see some kernel weirdness talking about timeouts talking to the USB-serial device. Perhaps something to investigate in the future.

Anyway running a 3G O2 PAYG (pay as you go) modem on Debian, on an EEEPC is possible, it is justfiddlier than I had expected, and it required an upgrade to Sid - since Lenny didn't have a network manager with mobile broadband support.

For google's benefit the modem is described by O2 as a "mobile broadband USB modem - E160". This appears under lsusb as :

Bus 001 Device 005: ID 12d1:1003 Huawei Technologies Co., Ltd.
E220 HSDPA Modem / E270 HSDPA/HSUPA Modem

Hope that helps somebody else spend less than 5 hours getting it working. I guess the friends who said "It just worked" were running Ubuntu and so had a slightly newer network manager by default - and possibly their modems didn't need to toggle between "dumb storage" and "actual modem" modes.

Anyway it works now, and even though it was fiddly the issue wasn't insurmountable. I'm just a little grumpy because I've gotten used to a world in which Debian just works - the last time I struggled to get new hardware toys playing nice was .. a long time ago.

ObFilm: Pretty In Pink

Tags: 3g, modems, network-manager, o2, usb. | 3 comments.