Digimer! Thanks for the info. Since the HDD0 drive is completely failed, I would need to replace it.. it doesn't have any data on it. The other three HDD's would need the MBR. I am assuming... that because RAID 10 means Striped+Mirroring that HDD 3+4 would be mirrored and 1+2 would be mirrored... is this an accurate statement?
On 3/2/2012 12:07 PM, Digimer wrote:
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.