mdstat - what is this?

[Mike Reinehr]

On Saturday 30 September 2006 08:08, Michael Hipp wrote:
> What's the md255 stuff below? I didn't create any such device.
>
> Thanks,
> Michael
>
> # cat /proc/mdstat
> Personalities : [raid1]
> md255 : active raid1 dm-4[1] dm-3[0]     <---
>        136351616 blocks [2/2] [UU]        <---
>
> md3 : active raid1 hdc2[1]
>        18787904 blocks [2/1] [_U]
>
> md2 : active raid1 hdc1[1]
>        104320 blocks [2/1] [_U]
>
> md1 : active raid1 hda4[0] hdc4[1]
>        136351616 blocks [2/2] [UU]
>
> md0 : active raid1 hda3[0] hdc3[1]
>        1044160 blocks [2/2] [UU]

Michael,

md255 looks suspiciously like md1. Have you tried using 
`mdadm --query --detail /dev/md255` to learn more about it? Are there any 
entries in your /dev directory named dm-?? Are you using udev? Perhaps this 
is some peculiar behavior of udev.

md now has persistent superblocks which will cause an array to be built on 
boot-up whether you have it defined in /etc/mdadm/mdadm.conf or not. Perhaps 
this is a leftover from some earlier raid array that you had set up once, but 
did not erase the superblock (I think that's unlikely, too, but you never 
know.)

Sorry I couldn't be more help.

cmr

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