On Fri, Jan 24, 2014 at 11:58 AM, Matt <matt.mailinglists at gmail.com> wrote: > I installed Centos 6.x 64 bit with the minimal ISO and used two disks > in RAID 1 array. > > Filesystem Size Used Avail Use% Mounted on > /dev/md2 97G 918M 91G 1% / > tmpfs 16G 0 16G 0% /dev/shm > /dev/md1 485M 54M 407M 12% /boot > /dev/md3 3.4T 198M 3.2T 1% /vz > > Personalities : [raid1] > md1 : active raid1 sda1[0] sdb1[1] > 511936 blocks super 1.0 [2/2] [UU] > md3 : active raid1 sda4[0] sdb4[1] > 3672901440 blocks super 1.1 [2/2] [UU] > bitmap: 0/28 pages [0KB], 65536KB chunk > md2 : active raid1 sdb3[1] sda3[0] > 102334336 blocks super 1.1 [2/2] [UU] > bitmap: 0/1 pages [0KB], 65536KB chunk > md0 : active raid1 sdb2[1] sda2[0] > 131006336 blocks super 1.1 [2/2] [UU] > > My question is if sda one fails will it still boot on sdb? Did the > install process write the boot sector on both disks or just sda? How > do I check and if its not on sdb how do I copy it there? > I've found that the grub boot loader is only installed on the first disk. When I do use software raid, I have made a habit of manually installing grub on the other disks (using grub-install). In most cases I dedicated a RAID1 array to the host OS and have a separate array for storage. You can check to see that a boot loader is present with `file`. ~]# file -s /dev/sda /dev/sda: x86 boot sector; partition 1: ID=0xfd, active, starthead 1, startsector 63, 224847 sectors; partition 2: ID=0xfd, starthead 0, startsector 224910, 4016250 sectors; partition 3: ID=0xfd, starthead 0, startsector 4241160, 66878595 sectors, code offset 0x48 There are other ways to verify the boot loader is present, but that's the one I remember off the top of my head. Use grub-install to install grub to the MBR of the other disk. > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > -- ---~~.~~--- Mike // SilverTip257 //