Entries tagged computers:gold

Related tags: mdadm, recovery, usb, usb booting.

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

Saturday, 14 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

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You are the witness of change

Saturday, 29 December 2007

As I wrote yesterday I've recently ordered, and now received a new desktop machine. For completeness I've now finished juggling machines around and installed etch twice - so now I have two working desktop machines:

gold.my.flat (unstable)

This is my personal machine, fitted with 4Gb of RAM.

It is currently running 6 xen instances of 256Mb each leaving me with more meory free than I have ever had upon my desktop machine - so the upgrade was definitely worthwhile!.

(The previous machine had bad sockets and couldn't take more than 1Gb of RAM - hence the replacement rather than mere upgrade.)

vain.my.flat (etch)

This, reinstalled, machine is now running only backuppc and those programs that Meg/random guests wish to run.

In terms of networking I've now split things up into three well-defined ranges. Knowing how things develop I'll not expect this to contining, but right now I'm pleased with:

  • 192.168.1.0/24
    • These two desktops, a printer, and any wired laptops that are turned on.
  • 10.0.0.0/24
    • Xen guests
  • 10.0.1.0/24
    • Wireless DHCP range.

All in all I'm very happy with the work of the day even if I did have to rsync stuff all over the place, juggle power cables and install Etch upon both the new machine, and the re-purposed backup machine. (Since that was previously my mahcine and was running sid.)

The following links were helpful.

All being well tomorrow will be spent tidying the flat, drinking with my erstwhile cat-sitter, and getting ready for work on Monday.

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