Re: Autodetect of software RAID1+0 fails

Craig,

to make things working properly here you need to create a config file
keeping both raid1 and raid0 information (/etc/mdadm/mdadm.conf).
However if your root filesystem is corrupted, or you loose this file,
or move disks somewhere else - you are back to the same initial issue
:))

So, the solution I've found 100% working in any case is: use mdadm to
create raid1 devices (as you do already) and then use LVM to create
raid0 volume on it - LVM writes its own labels on every MD devices and
will find its volumes peaces automatically! Tested for crash several
times and was surprised by its robustness :))

Rgds,
-Dimitri

On 6/1/07, Craig James <craig_james(at)emolecules(dot)com> wrote:
> Apologies for a somewhat off-topic question, but...
>
> The Linux kernel doesn't properly detect my software RAID1+0 when I boot up.
> It detects the two RAID1 arrays, the partitions of which are marked
> properly. But it can't find the RAID0 on top of that, because there's no
> corresponding device to auto-detect. The result is that it creates /dev/md0
> and /dev/md1 and assembles the RAID1 devices on bootup, but /dev/md2 isn't
> created, so the RAID0 can't be assembled at boot time.
>
> Here's what it looks like:
>
> $ cat /proc/mdstat
> Personalities : [raid0] [raid1]
> md2 : active raid0 md0[0] md1[1]
> 234436224 blocks 64k chunks
>
> md1 : active raid1 sde1[1] sdc1[2]
> 117218176 blocks [2/2] [UU]
>
> md0 : active raid1 sdd1[1] sdb1[0]
> 117218176 blocks [2/2] [UU]
>
> $ uname -r
> 2.6.12-1.1381_FC3
>
> After a reboot, I always have to do this:
>
> mknod /dev/md2 b 9 2
> mdadm --assemble /dev/md2 /dev/md0 /dev/md1
> mount /dev/md2
>
> What am I missing here?
>
> Thanks,
> Craig
>
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