[K12OSN] The "can't log in as root to fix the 'can't log in as root'" conundrum

[Carl Keil]

So, returning after break I found a problem with my Centos 5 server.  
It's a K12LTSP 5 EL 32 bit install.  I'm not serving thin clients with 
it, but hope to down the road.  I set it up so far to be a 
Samba/LDAP/homedir server.  I fired up the server and then logged into 
my ubuntu client authenticating via LDAP off the server just fine.  I 
wanted to adjust a configuration on the server so I tried to log in as 
root at the server's terminal.  I got a message saying that it couldn't 
log in as root because it couldn't find the folder /home/root.  This is 
really odd, because it was working fine before break with the usual 
/root folder and I never [knowingly] told it to use /home/root for the 
root folder.  Is there someway to log in and tell it to construct a new 
home folder for root if it can't find one?

I tried logging in via "linux rescue" and I tried to mount the main file 
system.  I was going to change /etc/passwd to have root's homedir be 
/root but it wouldn't let me mount /dev/sda2 .  /dev/sda1 is the boot 
partition and I'm pretty sure /dev/sda2 is the other stuff.  /dev/sda1 
stopped mounting on subsequent attempts even after rebooting, really 
weird.  I'm really flummoxed.  I don't know how this happened or what to 
do about it.  I can log in as other users just fine on the system, but I 
need a symlink or something for the /root folder.  One other 
complication is that /home is on a mirrored linux raid partition, so I 
don't know how to mount that in linux rescue mode, not that I can mount 
the main partition which isn't on RAID anyway.

Can someone suggest a fix?

Thanks,

ck