Les Mikesell wrote:
> CentOS List wrote:
>>> CentOS List wrote:
>>>>> CentOS List wrote:
>>>>>>>>>> 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.
>
>
>> 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?
Oops - that would be sda2/sdb2 there - they start from 0.
--
Les Mikesell
lesmikesell at gmail.com