[CentOS] CentOS 6.2 software raid 10 with LVM - Need help with degraded drive and only one MBR

Fri Mar 2 14:03:44 UTC 2012
Jonathan Vomacka <juvix88 at gmail.com>

CentOS Community,

I have a dedicated server with 4 hard drives in a RAID 10 software 
configuration running LVM. My OS is CentOS 6.2. Earlier today, I 
rebooted my system and my system did not come back online. I opened a 
ticket with my datacenter who informed me that one of my hard drives is 
no longer recognized by the bios and has failed. I was told that an OS 
reinstall was needed.

I don't understand why a reinstall would be necessary when the drives 
are in RAID 10. Apparently when the datacenter did the initial OS 
install, they ONLY installed the MBR on one drive instead of all 4 
leaving the other 3 drives unbootable.

Is this a way to salvage this with a liveCD without having to reload the 
OS? This server is a very important mail server running OpenLDAP and 
MySQL. I figured maybe I could install the MBR using a liveCD which may 
fix the system.

If an OS reload is the ONLY option, is there a way to reload it without 
touching the /var or /opt filesystems? (yes they were created as a 
seperate partition) however I am not sure if OpenLDAP or MySQL installs 
anything to /usr which I would be completely screwed...

Please help