Messed up creating new array...

Messed up creating new array...

[Ruth Ivimey-Cook]

Folks,

I messed up slightly when creating a new 6-disk raid6 array, and am wondering
if there is a simple answer. The problem is that I didn't partition the drives,
but simply used the whole drive. All drives are of the same type and using the
Supermicro SAT2-MV8 controller.

This is a problem because mdadm doesn't find the component drives... I can only
start the array by using "mdadm --assemble /dev/md3 /dev/sd{drives}". While
this works it means my system doesn't boot very easily :-(

For fixes I can think of the possible solutions:

 - Modify the startup script to do the mdadm --assemble /dev/md3
/dev/sd{a,b,c,d,e}. Is there any other disadvantage of this?

 - Use fdisk to create whole-disk partitions - but would this damage the
already stored data?

 - Start again doing it right.... But this will take >12 hours and has a chance
of failure!

Any thoughts?

Regards,

Ruth

Re: Messed up creating new array...

[David Rees]

On 9/8/06, Ruth Ivimey-Cook <Ruth.Ivimey-Cook@ivimey.org> wrote:
> I messed up slightly when creating a new 6-disk raid6 array, and am wondering
> if there is a simple answer. The problem is that I didn't partition the drives,
> but simply used the whole drive. All drives are of the same type and using the
> Supermicro SAT2-MV8 controller.

This should work:

1. Unmount filesystem.
2. Shrink file system to something a bit smaller. Since it's a big
array, 1GB should give you plenty of room.
3. Shrink raid array to something in between the new fs size and old
fs size. Make sure you don't shrink it smaller than the filesystem!
4. Remove a disk from the array (fail/remove)
5. Partition disk
6. Add partition back to array
7. Repeat steps 4-6 for all disks in the array.
8. Now the whole array should be on partitions. Grow the raid array
back to "max".
9. Grow filesystem to the partition size.

-Dave