Ubuntu Install on PowerEdge R300 , initramfs?

Same issue here, with the 64bit version. 

I saw a couple articles discussing various opinions and problems with installing related to the RAID itself...  So for grins I broke the raid and put the two drive to direct attach and tried to install again.   Same basic result...

I've tried with and without LVM, by the way.

I can see the proper devices in the busybox console, and they appear to be valid and accessible.  Yet the root partition is still reported as missing...

Let me know if you've solved your issue...  I'll keep trying on this side and will post if I find anything.

I solved the issue on my end... though I haven't verified it with the RAID configuration back in place (I want the extra HDD space and am willing to "live on the edge"...)

Basically, the SAS controller is verrrrry slow in booting. 

I was able to update my Grub by starting in recovery mode, hanging out at the busybox prompt for about 50secs, and then typing exit.  (funny story... I did this by accident, I meant to just reset, but my shell muscle memory overrode my hands and I typed exit instead)  The recovery mode script kicked in and I was able to select netroot and drop to a root console....  but I believe booting from the LiveCD, mounting your HD's and chroot-ing will do the same...  I can provide better, more detailed instructions on this if needed.

My default GRUB kernel line (in /boot/grub/menu.1st) stated something like this:

kernel          /boot/vmlinuz-2.6.28-11-server root=UUID=f2d0cd5c-088f-448b-a717-142127fa509f quiet ro splash

So I removed the "quiet" and tried booting... and got something to the tune of:

[ 0.00000000] (Message about boot starting that whips by faster than I can read)

......

[  7.35634345] No floppy controllers present

<-  I get the warning message about the "Can't find disk by UUID" here

(initramfs)

<- ...and then a couple seconds later I get something like

[ 35.4574445] (Messages about the SAS controller coming on line)

So the solution was to add:

rootdelay=50

to the kernel command line so you get:

/boot/vmlinuz-2.6.28-11-server root=UUID=f2d0cd5c-088f-448b-a717-142127fa509f rootdelay=50 quiet ro splash

A write and grub-install later...  and voila everything is happy. 

I do have to mention though, for sake of humility, all my research and testing was in vain.  The error message from the kernel right before it drops you to busybox actually says something like....

rootdelay= (Are we waiting long enough for the drives to come up?)(...er...uh... something like that.)

...yet another case of "Read the full error message before starting to diagnose."

Anyhow, I hope it helps.

The note below solved my issue.

http://ubuntuforums.org/archive/index.php/t-1063456.htm

Rohit