fixing raid1

fixing raid1

[jdd]

Hello,

I'm new to this mailing list, so forgive me if I break some etiquette

I have an academic problem. I mean that the target computer in not in 
production and do not hold any essential data. I try to learn some 
aspects of linux raid.

I have built a three disks raid1 on openSUSE 42.2. so far so good, all 
worked perfectly

but later on I had no more use of the machine with as much disks, and 
wanted to reclaim one disk. This one was in a esata dock.

At the moment I didn't found a way to make this cleanly (I found it it 
too late in the linux raid wiki 
https://raid.wiki.kernel.org/index.php/A_guide_to_mdadm#Removing_a_disk_from_an_array)

so, I stopped the computer and removed the dock.

The computer rebooted perfectly, but in slightly degraded mode (see below)

I don't find a way to tell the system that it have to forget the third 
disk. May be it's not necessary.

Do you have a clue?

thanks
jdd

# mdadm --detail /dev/md127
/dev/md127:
         Version : 1.0
   Creation Time : Wed Dec 21 22:43:31 2016
      Raid Level : raid1
      Array Size : 976758592 (931.51 GiB 1000.20 GB)
   Used Dev Size : 976758592 (931.51 GiB 1000.20 GB)
    Raid Devices : 3
   Total Devices : 2
     Persistence : Superblock is persistent

   Intent Bitmap : Internal

     Update Time : Mon May  1 15:29:48 2017
           State : clean, degraded
  Active Devices : 2
Working Devices : 2
  Failed Devices : 0
   Spare Devices : 0

            Name : any:jdd-raid
            UUID : 4d57c009:5d7fc724:07376d9a:8ecb39a2
          Events : 9592

     Number   Major   Minor   RaidDevice State
        0       8        1        0      active sync   /dev/sda1
        1       8       17        1      active sync   /dev/sdb1
        -       0        0        2      removed

Re: fixing raid1

[Roman Mamedov]

On Mon, 1 May 2017 18:34:14 +0200
"jdd@dodin.org" <jdd@dodin.org> wrote:

> I have built a three disks raid1 on openSUSE 42.2. so far so good, all 
> worked perfectly
> 
> but later on I had no more use of the machine with as much disks, and 
> wanted to reclaim one disk. This one was in a esata dock.
> 
> At the moment I didn't found a way to make this cleanly (I found it it 
> too late in the linux raid wiki 
> https://raid.wiki.kernel.org/index.php/A_guide_to_mdadm#Removing_a_disk_from_an_array)
>
> so, I stopped the computer and removed the dock.
> 
> The computer rebooted perfectly, but in slightly degraded mode (see below)
> 
> I don't find a way to tell the system that it have to forget the third 
> disk. May be it's not necessary.

It appears you just need to do the 2nd step as listed in that wiki,

  mdadm --grow /dev/md127 --raid-devices=2

Did you try it? 

> # mdadm --detail /dev/md127
> /dev/md127:
>          Version : 1.0
>    Creation Time : Wed Dec 21 22:43:31 2016
>       Raid Level : raid1
>       Array Size : 976758592 (931.51 GiB 1000.20 GB)
>    Used Dev Size : 976758592 (931.51 GiB 1000.20 GB)
>     Raid Devices : 3
>    Total Devices : 2
>      Persistence : Superblock is persistent
> 
>    Intent Bitmap : Internal
> 
>      Update Time : Mon May  1 15:29:48 2017
>            State : clean, degraded
>   Active Devices : 2
> Working Devices : 2
>   Failed Devices : 0
>    Spare Devices : 0
> 
>             Name : any:jdd-raid
>             UUID : 4d57c009:5d7fc724:07376d9a:8ecb39a2
>           Events : 9592
> 
>      Number   Major   Minor   RaidDevice State
>         0       8        1        0      active sync   /dev/sda1
>         1       8       17        1      active sync   /dev/sdb1
>         -       0        0        2      removed
> --
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-- 
With respect,
Roman

Re: fixing raid1

[jdd]

Le 01/05/2017 à 19:19, Roman Mamedov a écrit :

> It appears you just need to do the 2nd step as listed in that wiki,
>
>   mdadm --grow /dev/md127 --raid-devices=2
>
> Did you try it?


I didn't (grow... was thinking it was to make it bigger :-()

but it works perfectly

done

Thanks
jdd