On 01/24/2014 09:33 PM, Les Mikesell wrote: > On Fri, Jan 24, 2014 at 1:30 PM, Ljubomir Ljubojevic <centos at plnet.rs> wrote: >>> >>> and, even if you have the boot loader on both drives, there's no >>> guarantee your BIOS will boot from the 2nd one. Disks can partially >>> fail in nasty ways that might allow the already-running system to stay >>> up on the other half of the mirror, but when the drive is 'tested' >>> during power up boot sequence, it could hang the system. >>> >> >> True, but forwarding of root mail to admins e-mail address will warn >> about crash of mirror, so physical intervention of choice can be made. I >> think manual change in BIOS is of little consequence if system will boot >> off of surviving disk(s). > > Doesn't grub need to know the bios disk id for subsequent stages of > the boot and where to find the root filesystem? I think it matters > whether or not bios remaps your 2nd drive to the first id. GRUB boots first partition on a given disk, and then kernel boots file systems from RAID's. Once /boot RAID is mounted, any changes are written to all disks. > >> And if disks can be hot-swapped then only concern is that GRUB and /boot >> survive the crash. > > And if you know how to do a rescue-mode boot and reinstall grub, you > can fix that too. > -- Ljubomir Ljubojevic (Love is in the Air) PL Computers Serbia, Europe StarOS, Mikrotik and CentOS/RHEL/Linux consultant