Quoting Roberto Pereyra <pereyra.roberto at gmail.com>: > Hi > > I have a clean CentOS 4.4 disk and I have setup a RAID 1 with two IDE disk. > > The system RAID 1 boot fine but when I disconnect a disk (the first > disk) the system not boot. The screen goes black and not boot anything > (grub not boot). Where is the Grub installed? MBR or partition? If you've setup RAID-1 during installation, Anaconda should have installed it in partition, which would mean that it got automatically mirrored to second drive. If this is the case, most likely your BIOS is refusing to boot from second drive. Also check that partition that holds /boot (usually first partition on the disk) is marked as bootable (use fdisk). If you've installed on single drive, and setup RAID-1 after intallation manually chances are Grub is installed in MBR of first drive (Anaconda defaults to install Grub into MBR when installing on single drive). If that is the case, than it won't be automagically mirrored to second drive. You'll have to install it into second drive's MBR by hand, for example: http://www.8-p.ca/archives/3-Grub-and-RAID-1.html