On 03/02/2012 09:03 AM, Jonathan Vomacka wrote: > 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 Advice provided as-is. Boot from a live CD using the CentOS 6.2 install media. Once booted: <bash># grub <grub> root (hd0,0) <grub> setup (hd0) <grub> root (hd1,0) <grub> setup (hd1) <grub> root (hd2,0) <grub> setup (hd2) <grub> quit <bash># reboot This assumes that grub sees the drives at '0, 1 and 2' and the boot partition is the first on each drive. If it is, when you type 'root (hdX,0)' it should report that a file system was found. The 'setup (hdX)' will tell grub to write the MBR to the specified disk. -- Digimer E-Mail: digimer at alteeve.com Papers and Projects: https://alteeve.com