For a little over a year, my home server has been plugging away just fine. It had a 300GB IDE drive with ubuntu on it, and three 2TB drives on SATA ports in an mdadm RAID5 array.
I lost a drive last week, and it was suggested to just try restarting it before doing anything else. Since doing that, however, I've been completely unable to boot into a working ubuntu system without unplugging ALL of the 2TB drives. I've identified the failed drive, as it doesn't get recognized in bios at all, but when I plug either of the other working drives in, I can't start at all - even with a working live USB stick.
When trying to boot from the normal system hard drive, I still get the grub menu, so I know it's not an issue of which drive is being booted or anything like that.. it just goes to a black screen after grub and there is nothing written to /var/log/messages or dmesg for me to diagnose the next time.
When using a perfectly good live USB stick, it hangs on the line about loading .../vmlinuz.
Any advice/help would be appreciated.
Thanks to some super-sleuthing from some friends at work, I finally figured this one out. The problem is I had two mdadm-formatted disks in the computer, but not enough to cleanly start the volume. The solution was to boot without the drives connected, apt-get remove mdadm, then reboot with the drives plugged in again.
Then, I was able to re-install mdadm and perform the steps outlined here to finally have both the original booted system AND my intact data.