Adding a fresh drive to a degraded RAID1 (not as spare but instead of a "removed" device)

Adding a fresh drive to a degraded RAID1 (not as spare but instead of a "removed" device)

[Ciprian Dorin Craciun]

    Hello all!

    Although I've done this a couple of times before, I don't know
what I'm doing wrong here, but I can't add a device to a degraded
RAID1...

    My guess is that it's either from the feature "mix" or something
else that escapes me...
    * I use LVM2 as MD members; (this worked before, thus I would exclude this;)
    * I use "write intent bitmap";
    * I use "write mostly"; (this has also worked before...)

    Here are my commands:
    * I create the degraded MD device:
~~~~
mdadm \
    --verbose \
    --create \
    /dev/md/raid \
    --level=raid1 \
    --metadata=1.0 \
    --raid-devices=3 \
    --spare-devices=0 \
    --write-behind=1024 \
    --bitmap=internal \
    --bitmap-chunk=1M \
    --name=raid-device \
    --auto=md \
    /dev/mapper/raid-member-1 \
    missing \
    missing
~~~~
    * I then create an Ext2 file system and fill it;
    * I then intend to add a new device to the mirror:
~~~~
mdadm \
    --verbose \
    --manage \
    /dev/md/raid \
    --add \
    --write-mostly \
    /dev/mapper/raid-member-2
~~~~

    Unfortunately the `raid-member-2` appears as faulty and refuses to
be added... Initially this disk was all `0x00`... But I've also tried
to "zero" the superblock. (The block device is writable because I can
zero it...)
~~~~
mdadm \
    --zero-superblock \
    --metadata=1.0 \
    /dev/mapper/raid-member-2
~~~~

    The output of query gives:
~~~~
        Version : 1.0
  Creation Time : Sat Dec 29 15:44:26 2012
     Raid Level : raid1
     Array Size : 67108736 (64.00 GiB 68.72 GB)
  Used Dev Size : 67108736 (64.00 GiB 68.72 GB)
   Raid Devices : 3
  Total Devices : 2
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Sat Dec 29 22:56:15 2012
          State : active, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 1
  Spare Devices : 0

           Name : ...
           UUID : ...
         Events : 591

    Number   Major   Minor   RaidDevice State
       0     254        0        0      active sync   /dev/dm-0
       1       0        0        1      removed
       2       0        0        2      removed

       3     254        1        -      faulty writemostly spare   /dev/dm-1
~~~~

    I'm just lost... :)

    Thanks for the help,
    Ciprian.

Re: Adding a fresh drive to a degraded RAID1 (not as spare but instead of a "removed" device)

[Ciprian Dorin Craciun]

    Any feedback on this issue? (I guessed that the initial email was
overlooked due to the holidays. :) )

    Thanks,
    Ciprian.


On Sat, Dec 29, 2012 at 10:52 PM, Ciprian Dorin Craciun
<ciprian.craciun@gmail.com> wrote:
>     Hello all!
>
>     Although I've done this a couple of times before, I don't know
> what I'm doing wrong here, but I can't add a device to a degraded
> RAID1...
>
>     My guess is that it's either from the feature "mix" or something
> else that escapes me...
>     * I use LVM2 as MD members; (this worked before, thus I would exclude this;)
>     * I use "write intent bitmap";
>     * I use "write mostly"; (this has also worked before...)
>
>     Here are my commands:
>     * I create the degraded MD device:
> ~~~~
> mdadm \
>     --verbose \
>     --create \
>     /dev/md/raid \
>     --level=raid1 \
>     --metadata=1.0 \
>     --raid-devices=3 \
>     --spare-devices=0 \
>     --write-behind=1024 \
>     --bitmap=internal \
>     --bitmap-chunk=1M \
>     --name=raid-device \
>     --auto=md \
>     /dev/mapper/raid-member-1 \
>     missing \
>     missing
> ~~~~
>     * I then create an Ext2 file system and fill it;
>     * I then intend to add a new device to the mirror:
> ~~~~
> mdadm \
>     --verbose \
>     --manage \
>     /dev/md/raid \
>     --add \
>     --write-mostly \
>     /dev/mapper/raid-member-2
> ~~~~
>
>     Unfortunately the `raid-member-2` appears as faulty and refuses to
> be added... Initially this disk was all `0x00`... But I've also tried
> to "zero" the superblock. (The block device is writable because I can
> zero it...)
> ~~~~
> mdadm \
>     --zero-superblock \
>     --metadata=1.0 \
>     /dev/mapper/raid-member-2
> ~~~~
>
>     The output of query gives:
> ~~~~
>         Version : 1.0
>   Creation Time : Sat Dec 29 15:44:26 2012
>      Raid Level : raid1
>      Array Size : 67108736 (64.00 GiB 68.72 GB)
>   Used Dev Size : 67108736 (64.00 GiB 68.72 GB)
>    Raid Devices : 3
>   Total Devices : 2
>     Persistence : Superblock is persistent
>
>   Intent Bitmap : Internal
>
>     Update Time : Sat Dec 29 22:56:15 2012
>           State : active, degraded
>  Active Devices : 1
> Working Devices : 1
>  Failed Devices : 1
>   Spare Devices : 0
>
>            Name : ...
>            UUID : ...
>          Events : 591
>
>     Number   Major   Minor   RaidDevice State
>        0     254        0        0      active sync   /dev/dm-0
>        1       0        0        1      removed
>        2       0        0        2      removed
>
>        3     254        1        -      faulty writemostly spare   /dev/dm-1
> ~~~~
>
>     I'm just lost... :)
>
>     Thanks for the help,
>     Ciprian.