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* md raid recovery - perplexed
@ 2012-04-21  0:48 Ken Gunderson
  2012-04-21 17:29 ` Ken Gunderson
  0 siblings, 1 reply; 3+ messages in thread
From: Ken Gunderson @ 2012-04-21  0:48 UTC (permalink / raw)
  To: linux-raid

Hello List:

I've created some arrays.  For example, md2 is RAID1 created with gpt
based partitions  /dev/sd[ab]1

# mdadm --misc --detail /dev/md2

/dev/md2:
        Version : 1.0
  Creation Time : Thu Apr 19 15:56:18 2012
     Raid Level : raid1
     Array Size : 262132 (256.03 MiB 268.42 MB)
  Used Dev Size : 262132 (256.03 MiB 268.42 MB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Fri Apr 20 09:08:11 2012
          State : clean 
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : archiso:2
           UUID : e3a5c30e:3fb61039:397992ff:6cc70600
         Events : 17

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


Okay, great, that works.  However, I am not able to recover from
simulated failure.

# mdadm /dev/md2 --fail /dev/sdb1

# mdadm /dev/md2 --misc --detail

/dev/md2:
        Version : 1.0
  Creation Time : Thu Apr 19 15:56:18 2012
     Raid Level : raid1
     Array Size : 262132 (256.03 MiB 268.42 MB)
  Used Dev Size : 262132 (256.03 MiB 268.42 MB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Fri Apr 20 15:40:10 2012
          State : clean, degraded 
 Active Devices : 1
Working Devices : 1
 Failed Devices : 1
  Spare Devices : 0

           Name : archiso:2
           UUID : e3a5c30e:3fb61039:397992ff:6cc70600
         Events : 20

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

       1       8       17        -      faulty spare   /dev/sdb1



Followed by

# mdadm /dev/md2 --remove /dev/sdb1

/dev/md2:
        Version : 1.0
  Creation Time : Thu Apr 19 15:56:18 2012
     Raid Level : raid1
     Array Size : 262132 (256.03 MiB 268.42 MB)
  Used Dev Size : 262132 (256.03 MiB 268.42 MB)
   Raid Devices : 2
  Total Devices : 1
    Persistence : Superblock is persistent

    Update Time : Fri Apr 20 15:59:52 2012
          State : clean, degraded 
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           Name : archiso:2
           UUID : e3a5c30e:3fb61039:397992ff:6cc70600
         Events : 31

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


I should then be able to re-add sdb1, no?

# mdadm /dev/md2 --re-add /dev/sdb1

mdadm: --re-add for /dev/sdb1 to /dev/md2 is not possible

Since man mdadm explicitly provides following as example:

"mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1"

Let's try just adding it instead of re-adding

# mdadm /dev/md2 -a /dev/sdb1
mdadm: /dev/sdb1 reports being an active member for /dev/md2, but a --re-add fails.
mdadm: not performing --add as that would convert /dev/sdb1 in to a spare.
mdadm: To make this a spare, use "mdadm --zero-superblock /dev/sdb1" first.

I am perplexed as to why might this be?  I must be missing something
pretty basic here, else I can provide additional detail as require.

Thanks for your help-- Ken

-- 
Ken Gunderson <kgunders@teamcool.net>


^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: md raid recovery - perplexed
  2012-04-21  0:48 md raid recovery - perplexed Ken Gunderson
@ 2012-04-21 17:29 ` Ken Gunderson
  2012-04-26  2:50   ` Bill Davidsen
  0 siblings, 1 reply; 3+ messages in thread
From: Ken Gunderson @ 2012-04-21 17:29 UTC (permalink / raw)
  To: linux-raid


On Fri, 2012-04-20 at 18:48 -0600, Ken Gunderson wrote:
> Hello List:
> 
> I've created some arrays.  For example, md2 is RAID1 created with gpt
> based partitions  /dev/sd[ab]1
> 
> # mdadm --misc --detail /dev/md2
> 
> /dev/md2:
>         Version : 1.0
>   Creation Time : Thu Apr 19 15:56:18 2012
>      Raid Level : raid1
>      Array Size : 262132 (256.03 MiB 268.42 MB)
>   Used Dev Size : 262132 (256.03 MiB 268.42 MB)
>    Raid Devices : 2
>   Total Devices : 2
>     Persistence : Superblock is persistent
> 
>     Update Time : Fri Apr 20 09:08:11 2012
>           State : clean 
>  Active Devices : 2
> Working Devices : 2
>  Failed Devices : 0
>   Spare Devices : 0
> 
>            Name : archiso:2
>            UUID : e3a5c30e:3fb61039:397992ff:6cc70600
>          Events : 17
> 
>     Number   Major   Minor   RaidDevice State
>        0       8        1        0      active sync   /dev/sda1
>        1       8       17        1      active sync   /dev/sdb1
> 
> 
> Okay, great, that works.  However, I am not able to recover from
> simulated failure.
> 
> # mdadm /dev/md2 --fail /dev/sdb1
> 
> # mdadm /dev/md2 --misc --detail
> 
> /dev/md2:
>         Version : 1.0
>   Creation Time : Thu Apr 19 15:56:18 2012
>      Raid Level : raid1
>      Array Size : 262132 (256.03 MiB 268.42 MB)
>   Used Dev Size : 262132 (256.03 MiB 268.42 MB)
>    Raid Devices : 2
>   Total Devices : 2
>     Persistence : Superblock is persistent
> 
>     Update Time : Fri Apr 20 15:40:10 2012
>           State : clean, degraded 
>  Active Devices : 1
> Working Devices : 1
>  Failed Devices : 1
>   Spare Devices : 0
> 
>            Name : archiso:2
>            UUID : e3a5c30e:3fb61039:397992ff:6cc70600
>          Events : 20
> 
>     Number   Major   Minor   RaidDevice State
>        0       8        1        0      active sync   /dev/sda1
>        1       0        0        1      removed
> 
>        1       8       17        -      faulty spare   /dev/sdb1
> 
> 
> 
> Followed by
> 
> # mdadm /dev/md2 --remove /dev/sdb1
> 
> /dev/md2:
>         Version : 1.0
>   Creation Time : Thu Apr 19 15:56:18 2012
>      Raid Level : raid1
>      Array Size : 262132 (256.03 MiB 268.42 MB)
>   Used Dev Size : 262132 (256.03 MiB 268.42 MB)
>    Raid Devices : 2
>   Total Devices : 1
>     Persistence : Superblock is persistent
> 
>     Update Time : Fri Apr 20 15:59:52 2012
>           State : clean, degraded 
>  Active Devices : 1
> Working Devices : 1
>  Failed Devices : 0
>   Spare Devices : 0
> 
>            Name : archiso:2
>            UUID : e3a5c30e:3fb61039:397992ff:6cc70600
>          Events : 31
> 
>     Number   Major   Minor   RaidDevice State
>        0       8        1        0      active sync   /dev/sda1
>        1       0        0        1      removed
> 
> 
> I should then be able to re-add sdb1, no?
> 
> # mdadm /dev/md2 --re-add /dev/sdb1
> 
> mdadm: --re-add for /dev/sdb1 to /dev/md2 is not possible
> 
> Since man mdadm explicitly provides following as example:
> 
> "mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1"
> 
> Let's try just adding it instead of re-adding
> 
> # mdadm /dev/md2 -a /dev/sdb1
> mdadm: /dev/sdb1 reports being an active member for /dev/md2, but a --re-add fails.
> mdadm: not performing --add as that would convert /dev/sdb1 in to a spare.
> mdadm: To make this a spare, use "mdadm --zero-superblock /dev/sdb1" first.
> 
> I am perplexed as to why might this be?  I must be missing something
> pretty basic here, else I can provide additional detail as require.
> 
> Thanks for your help-- Ken
> 

btw - I  do get it that /dev/sdb1 still thinks it's an active member
of /dev/md2:

# mdadm -E /dev/sdb1
/dev/sdb1:
          Magic : a92b4efc
        Version : 1.0
    Feature Map : 0x0
     Array UUID : e3a5c30e:3fb61039:397992ff:6cc70600
           Name : archiso:2
  Creation Time : Thu Apr 19 15:56:18 2012
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 524264 (256.03 MiB 268.42 MB)
     Array Size : 524264 (256.03 MiB 268.42 MB)
   Super Offset : 524272 sectors
          State : clean
    Device UUID : 68d2dc69:03f902eb:9c8ca454:27bd3854

    Update Time : Fri Apr 20 09:46:57 2012
       Checksum : 2fa4f67c - correct
         Events : 17


   Device Role : Active device 1
   Array State : AA ('A' == active, '.' == missing)


And that I could --zero-superblock and then add the partition back into
the array.

And also that from searching the web that others encountering this seem
to solve the issue by utilizing an write bitmap. 

But from my reading of the documentation I should not have to, no?

Thanks in advance for helping me understand what's actually going on
here.


-- 
Ken Gunderson <kgunders@teamcool.net>


^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: md raid recovery - perplexed
  2012-04-21 17:29 ` Ken Gunderson
@ 2012-04-26  2:50   ` Bill Davidsen
  0 siblings, 0 replies; 3+ messages in thread
From: Bill Davidsen @ 2012-04-26  2:50 UTC (permalink / raw)
  To: Linux RAID

Ken Gunderson wrote:
>
> On Fri, 2012-04-20 at 18:48 -0600, Ken Gunderson wrote:
>> Hello List:
>>
>> I've created some arrays.  For example, md2 is RAID1 created with gpt
>> based partitions  /dev/sd[ab]1
>>
>> # mdadm --misc --detail /dev/md2
>>
>> /dev/md2:
>>          Version : 1.0
>>    Creation Time : Thu Apr 19 15:56:18 2012
>>       Raid Level : raid1
>>       Array Size : 262132 (256.03 MiB 268.42 MB)
>>    Used Dev Size : 262132 (256.03 MiB 268.42 MB)
>>     Raid Devices : 2
>>    Total Devices : 2
>>      Persistence : Superblock is persistent
>>
>>      Update Time : Fri Apr 20 09:08:11 2012
>>            State : clean
>>   Active Devices : 2
>> Working Devices : 2
>>   Failed Devices : 0
>>    Spare Devices : 0
>>
>>             Name : archiso:2
>>             UUID : e3a5c30e:3fb61039:397992ff:6cc70600
>>           Events : 17
>>
>>      Number   Major   Minor   RaidDevice State
>>         0       8        1        0      active sync   /dev/sda1
>>         1       8       17        1      active sync   /dev/sdb1
>>
>>
>> Okay, great, that works.  However, I am not able to recover from
>> simulated failure.
>>
>> # mdadm /dev/md2 --fail /dev/sdb1
>>
>> # mdadm /dev/md2 --misc --detail
>>
>> /dev/md2:
>>          Version : 1.0
>>    Creation Time : Thu Apr 19 15:56:18 2012
>>       Raid Level : raid1
>>       Array Size : 262132 (256.03 MiB 268.42 MB)
>>    Used Dev Size : 262132 (256.03 MiB 268.42 MB)
>>     Raid Devices : 2
>>    Total Devices : 2
>>      Persistence : Superblock is persistent
>>
>>      Update Time : Fri Apr 20 15:40:10 2012
>>            State : clean, degraded
>>   Active Devices : 1
>> Working Devices : 1
>>   Failed Devices : 1
>>    Spare Devices : 0
>>
>>             Name : archiso:2
>>             UUID : e3a5c30e:3fb61039:397992ff:6cc70600
>>           Events : 20
>>
>>      Number   Major   Minor   RaidDevice State
>>         0       8        1        0      active sync   /dev/sda1
>>         1       0        0        1      removed
>>
>>         1       8       17        -      faulty spare   /dev/sdb1
>>
>>
>>
>> Followed by
>>
>> # mdadm /dev/md2 --remove /dev/sdb1
>>
>> /dev/md2:
>>          Version : 1.0
>>    Creation Time : Thu Apr 19 15:56:18 2012
>>       Raid Level : raid1
>>       Array Size : 262132 (256.03 MiB 268.42 MB)
>>    Used Dev Size : 262132 (256.03 MiB 268.42 MB)
>>     Raid Devices : 2
>>    Total Devices : 1
>>      Persistence : Superblock is persistent
>>
>>      Update Time : Fri Apr 20 15:59:52 2012
>>            State : clean, degraded
>>   Active Devices : 1
>> Working Devices : 1
>>   Failed Devices : 0
>>    Spare Devices : 0
>>
>>             Name : archiso:2
>>             UUID : e3a5c30e:3fb61039:397992ff:6cc70600
>>           Events : 31
>>
>>      Number   Major   Minor   RaidDevice State
>>         0       8        1        0      active sync   /dev/sda1
>>         1       0        0        1      removed
>>
>>
>> I should then be able to re-add sdb1, no?
>>
>> # mdadm /dev/md2 --re-add /dev/sdb1
>>
>> mdadm: --re-add for /dev/sdb1 to /dev/md2 is not possible
>>
>> Since man mdadm explicitly provides following as example:
>>
>> "mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1"
>>
>> Let's try just adding it instead of re-adding
>>
>> # mdadm /dev/md2 -a /dev/sdb1
>> mdadm: /dev/sdb1 reports being an active member for /dev/md2, but a --re-add fails.
>> mdadm: not performing --add as that would convert /dev/sdb1 in to a spare.
>> mdadm: To make this a spare, use "mdadm --zero-superblock /dev/sdb1" first.
>>
>> I am perplexed as to why might this be?  I must be missing something
>> pretty basic here, else I can provide additional detail as require.
>>
>> Thanks for your help-- Ken
>>
>
> btw - I  do get it that /dev/sdb1 still thinks it's an active member
> of /dev/md2:
>
> # mdadm -E /dev/sdb1
> /dev/sdb1:
>            Magic : a92b4efc
>          Version : 1.0
>      Feature Map : 0x0
>       Array UUID : e3a5c30e:3fb61039:397992ff:6cc70600
>             Name : archiso:2
>    Creation Time : Thu Apr 19 15:56:18 2012
>       Raid Level : raid1
>     Raid Devices : 2
>
>   Avail Dev Size : 524264 (256.03 MiB 268.42 MB)
>       Array Size : 524264 (256.03 MiB 268.42 MB)
>     Super Offset : 524272 sectors
>            State : clean
>      Device UUID : 68d2dc69:03f902eb:9c8ca454:27bd3854
>
>      Update Time : Fri Apr 20 09:46:57 2012
>         Checksum : 2fa4f67c - correct
>           Events : 17
>
>
>     Device Role : Active device 1
>     Array State : AA ('A' == active, '.' == missing)
>
>
> And that I could --zero-superblock and then add the partition back into
> the array.
>
> And also that from searching the web that others encountering this seem
> to solve the issue by utilizing an write bitmap.
>
> But from my reading of the documentation I should not have to, no?
>
I think the problem is in the documentation, it should tell you these things 
perhaps. I confess I learned about this the easy way, since I have always used a 
bitmap and not encountered this until I was testing a similar post years ago.

You might be able to --force it, but I'd rather zero the superblock myself, I 
don't like using the big hammer unless there's no "right" way. I think you do 
understand it, at least as well as I do.

> Thanks in advance for helping me understand what's actually going on
> here.
>
>


-- 
Bill Davidsen <davidsen@tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2012-04-26  2:50 UTC | newest]

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2012-04-21  0:48 md raid recovery - perplexed Ken Gunderson
2012-04-21 17:29 ` Ken Gunderson
2012-04-26  2:50   ` Bill Davidsen

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