Add a spare to a poorly defined raid1

Add a spare to a poorly defined raid1

[David Liontooth]

Not knowing what I was doing, I created a RAID1 with a single drive and 
a spare, as below.

I'd like to add the spare to the array. How do I do this without rebooting?

Cheers,
Dave


# definitions of existing MD arrays
ARRAY /dev/md0 level=raid1 num-devices=1 
UUID=9921faab:5d93510e:0db287f1:dc103b07
    spares=1

# mdadm --detail /dev/md0
/dev/md0:
         Version : 0.90
   Creation Time : Fri Jul 18 14:57:40 2008
      Raid Level : raid1
      Array Size : 104320 (101.89 MiB 106.82 MB)
   Used Dev Size : 104320 (101.89 MiB 106.82 MB)
    Raid Devices : 1
   Total Devices : 2
Preferred Minor : 0
     Persistence : Superblock is persistent

     Update Time : Wed Feb 15 03:37:11 2012
           State : clean
  Active Devices : 1
Working Devices : 2
  Failed Devices : 0
   Spare Devices : 1

            UUID : 9921faab:5d93510e:0db287f1:dc103b07
          Events : 0.218

     Number   Major   Minor   RaidDevice State
        0       8        1        0      active sync   /dev/sda1

        1       8       17        -      spare   /dev/sdb1

Re: Add a spare to a poorly defined raid1

[Robin Hill]

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On Wed Feb 15, 2012 at 05:51:12 +0530, David Liontooth wrote:

> 
> Not knowing what I was doing, I created a RAID1 with a single drive and 
> a spare, as below.
> 
> I'd like to add the spare to the array. How do I do this without rebooting?
> 
> Cheers,
> Dave
> 
> 
> # definitions of existing MD arrays
> ARRAY /dev/md0 level=raid1 num-devices=1 
> UUID=9921faab:5d93510e:0db287f1:dc103b07
>     spares=1
> 
> # mdadm --detail /dev/md0
> /dev/md0:
>          Version : 0.90
>    Creation Time : Fri Jul 18 14:57:40 2008
>       Raid Level : raid1
>       Array Size : 104320 (101.89 MiB 106.82 MB)
>    Used Dev Size : 104320 (101.89 MiB 106.82 MB)
>     Raid Devices : 1
>    Total Devices : 2
> Preferred Minor : 0
>      Persistence : Superblock is persistent
> 
>      Update Time : Wed Feb 15 03:37:11 2012
>            State : clean
>   Active Devices : 1
> Working Devices : 2
>   Failed Devices : 0
>    Spare Devices : 1
> 
>             UUID : 9921faab:5d93510e:0db287f1:dc103b07
>           Events : 0.218
> 
>      Number   Major   Minor   RaidDevice State
>         0       8        1        0      active sync   /dev/sda1
> 
>         1       8       17        -      spare   /dev/sdb1
> 

That's a straightforward one - you just need to increase the number of
active members in the array:

    mdadm --grow /dev/md0 -n 2

Cheers,
    Robin
-- 
     ___        
    ( ' }     |       Robin Hill        <robin@robinhill.me.uk> |
   / / )      | Little Jim says ....                            |
  // !!       |      "He fallen in de water !!"                 |

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Re: Add a spare to a poorly defined raid1

[David Liontooth]

On 02/15/2012 06:14 PM, Robin Hill wrote:
> mdadm --grow /dev/md0 -n 2
Perfect, thank you!