Rebuild Linux raid1 after os reinstall

view story

http://serverfault.com – I have 4 disks in my server. sda and sdb were combined to RAID1 and had the operating system. sdc and sdd were a second RAID1 device that had a single volume group with a bunch of LVMs. sdd died so my data RAID got degraded. After replacing sdd (but before adding to the RAID), grub decided lose it's mind and refuse to boot. The fastest way to fix was to just reinstall the OS since there was nothing important on it. I removed sdc and sdd during the install to make sure they were not overwritten by mistake. After the install was finished, I put the drives back in, and Centos found my volume (HowTos)