[CentOS] raid on large disks?

[Les Mikesell]

On Wed, Oct 12, 2011 at 11:37 AM, David C. Miller
<millerdc at fusion.gat.com> wrote:
>
>> Not booting from them, but is there a problem with kernel
>> autoassembly
>> on large partitions?  I see this in dmsg:
>>
>> md: Autodetecting RAID arrays.
>> md: invalid raid superblock magic on sde1
>> md: sde1 has invalid sb, not importing!
>>
>> But
>> mdadm --assemble /dev/md5 /dev/sde1
>> works fine after booting.  (The array was created with a missing
>> member which hasn't been added yet).
>>
>
> When using mdadm you don't even have to partition a drive if you are using the whole thing. Just make sure the block device is set to GPT in parted if it is not already. After creating the RAID1 get the uuid of the raid by doing mdadm -D /dev/dm5. Then use the following format in the /etc/mdadm.conf to have it auto assemble at boot.
>
> ARRAY /dev/md5 devices=/dev/sd[e-f] uuid=$UUID_FROM_MDADM

Thanks - I already had the raid and filesystem (and data) on a
partition - it just wasn't restarting at boot. The above approach with
the device names of the partitions seems to bring it up in time to
make it work when included in /etc/fstab.   That's better than
nothing, but I'd really prefer kernel autoassembly because the disks
are all in swappable enclosures and I do move things around once in a
while.  Does that just not work for large partitions?  I see that 'cat
/proc/mdstat' says 'super 1.0' on this device and none of the others.

-- 
  Les Mikesell
    lesmikesell at gmail.com