>>>>>>>>>> I am running raid 1 on a centos 4.4. One of the harddisk (sda1) >>>>>>>>>> failed. How can i carry on running the server using only sda2? >>>>>>>>> >>>>>>>>> Generate a grub floppy and use that to load the grub menu from >>>>>>>>> the sdb (probably now sda) disk. >>>>>>>>> >>>>>>>>> If you are really talking about sda1 and sda2, those are >>>>>>>>> partitions on the same disk. >>>>>>>> >>>>>>>> Is there a detail step by step howto? The raid 1 has no LVM. just >>>>>>>> md0, md1 and md2. md0 is /boot, md1 is swap and md2 is the >>>>>>>> storage. I had replace sba with a new disk. I tried to boot up >>>>>>>> and it says kernel panic. How am i going to reconstruct the raid >>>>>>>> and sync sdb to sda? >>>>>>> >>>>>>> It might be easier to swap the old sdb into the sda position so >>>>>>> you'll boot from it, but you should also be able to boot the >>>>>>> install cd with >>>>>> >>>>>> If swapped and booted, and got a kernel panic error. >>>>> >>>>>>> 'linux rescue' at the boot prompt, let it detect and mount your >>>>>>> system (which will be the 'broken' raid devices with their single >>>>>>> members), >>>>>> >>>>>> If i use linux rescue, The 3 mds I created are gone. /cat >>>>>> /proc/mdstat says Personalitlies: [raid0] [raid1] [raid5] [raid6], >>>>>> no longer Personalities : [raid1] >>>>> >>>>> Perhaps your raid wasn't really working the way you thought before. >>>>> From the rescue boot, does fdisk show the 3 partitions on the old >>>>> disk with type 'fd'? Can you mount the old /boot and / partitions >>>>> somewhere by hand? You should be able to do this with the /dev/sda1 >>>>> and /dev/sda3 device names if the md devices aren't detected at boot. >>>> >>>> cat /proc/partitions still shows me the 3 partitions. >>> >>> Does fdisk say that they are type 'fd'(raid autodetect)? >>> >>>> I actually copied /boot to the "replaced disk" and it is able to boot >>>> up, but without any filesystem, so i guess the boot is still intact. >>>> So do i need to mount /boot and /? >>> >>> If you can get the original partitions to be detected as their md >>> devices you should fdisk matching partitions on the replacement disk, >>> then 'mdadm --add ...' to add them and they will automatically sync up. >> >> mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sda1 >> /dev/sdb1 >> mdadm --create --verbose /dev/md1 --level=1 --raid-devices=2 /dev/sda2 >> /dev/sdb2 >> mdadm --create --verbose /dev/md2 --level=1 --raid-devices=2 /dev/sda3 >> /dev/sdb3 > > If you already had raid devices on one of the disks you should not have > had to --create them again. The original ones should have been detected > and you should have been able to --add new matching partitions. I created them as md(s) are not longer there. > >> After that i reboot and got the kernel panic again. >> >> md: considering sdb1 >> md: adding sdb1 >> md: created md0 >> md: bind<sda1> >> md: running: <sdb1><sda1> >> raid1: raid set md0 active with 2 out of 2 mirrors >> md: ... autorun DONE >> md: autodetcting RAID arrays >> md:mautorun ... >> Creating root device >> Mounting root filesystem >> switching to new root >> switchroot: mount failed: 22 >> umount /unitrd/dev failed: 2 >> Kernel panic > > When you --create a new raid it will start to sync the mirrors. It may > have done this the wrong direction, overwriting your old contents. Can > you still do a rescue mode boot, mount /dev/sda3 (or sdb3 if the old > drive is in the 2nd position) and see the contents? I am unable to mount sda3. # mount /dev/sda3 /mnt/part3 mount: Mounting /dev/sda3 on /mnt failed: Invalid argument sdb is not longer detectable.