where is the spare drive? :-)

where is the spare drive? :-)

[JaniD++]

Hello, list,

I found something interesting when i try to create a brand new array on
brand new drives....

1. The command was:
mdadm --create /dev/md1 --level=5 --raid-devices=12 --chunk=1024 \
/dev/hda2 /dev/hdb2 /dev/hdc2 /dev/hdd2 \
/dev/sda2 /dev/sdb2 /dev/sdc2 /dev/sdd2 \
/dev/sde2 /dev/sdf2 /dev/sdg2 /dev/sdh2

2. The proc/mdstat:
Personalities : [linear] [raid0] [raid1] [raid5] [multipath] [raid6]
[raid10] [f
aulty]
md1 : active raid5 sdh2[12] sdg2[10] sdf2[9] sde2[8] sdd2[7] sdc2[6] sdb2[5]
sda
2[4] hdd2[3] hdc2[2] hdb2[1] hda2[0]
      2148934656 blocks level 5, 1024k chunk, algorithm 2 [12/11]
[UUUUUUUUUUU_]
      [=>...................]  recovery =  5.7% (11308928/195357696)
finish=234.
3min speed=13088K/sec

unused devices: <none>

3. The mdadm -D
/dev/md1:
        Version : 00.90.02
  Creation Time : Sat Dec 31 12:59:51 2005
     Raid Level : raid5
     Array Size : 2148934656 (2049.38 GiB 2200.51 GB)
    Device Size : 195357696 (186.31 GiB 200.05 GB)
   Raid Devices : 12
  Total Devices : 12
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Sat Dec 31 12:59:51 2005
          State : clean, degraded, recovering
 Active Devices : 11
Working Devices : 12
 Failed Devices : 0
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 1024K

 Rebuild Status : 6% complete

           UUID : 03cbaf43:19a629d2:0886920c:a696f7af
         Events : 0.1

    Number   Major   Minor   RaidDevice State
       0       3        2        0      active sync   /dev/hda2
       1       3       66        1      active sync   /dev/hdb2
       2      22        2        2      active sync   /dev/hdc2
       3      22       66        3      active sync   /dev/hdd2
       4       8        2        4      active sync   /dev/sda2
       5       8       18        5      active sync   /dev/sdb2
       6       8       34        6      active sync   /dev/sdc2
       7       8       50        7      active sync   /dev/sdd2
       8       8       66        8      active sync   /dev/sde2
       9       8       82        9      active sync   /dev/sdf2
      10       8       98       10      active sync   /dev/sdg2
      12       8      114       11      spare rebuilding   /dev/sdh2


4. The end of the dmesg
md: bind<hda2>
md: bind<hdb2>
md: bind<hdc2>
md: bind<hdd2>
md: bind<sda2>
md: bind<sdb2>
md: bind<sdc2>
md: bind<sdd2>
md: bind<sde2>
md: bind<sdf2>
md: bind<sdg2>
md: bind<sdh2>
raid5: device sdg2 operational as raid disk 10
raid5: device sdf2 operational as raid disk 9
raid5: device sde2 operational as raid disk 8
raid5: device sdd2 operational as raid disk 7
raid5: device sdc2 operational as raid disk 6
raid5: device sdb2 operational as raid disk 5
raid5: device sda2 operational as raid disk 4
raid5: device hdd2 operational as raid disk 3
raid5: device hdc2 operational as raid disk 2
raid5: device hdb2 operational as raid disk 1
raid5: device hda2 operational as raid disk 0
raid5: allocated 12531kB for md1
raid5: raid level 5 set md1 active with 11 out of 12 devices, algorithm 2
RAID5 conf printout:
 --- rd:12 wd:11 fd:1
 disk 0, o:1, dev:hda2
 disk 1, o:1, dev:hdb2
 disk 2, o:1, dev:hdc2
 disk 3, o:1, dev:hdd2
 disk 4, o:1, dev:sda2
 disk 5, o:1, dev:sdb2
 disk 6, o:1, dev:sdc2
 disk 7, o:1, dev:sdd2
 disk 8, o:1, dev:sde2
 disk 9, o:1, dev:sdf2
 disk 10, o:1, dev:sdg2
RAID5 conf printout:
 --- rd:12 wd:11 fd:1
 disk 0, o:1, dev:hda2
 disk 1, o:1, dev:hdb2
 disk 2, o:1, dev:hdc2
 disk 3, o:1, dev:hdd2
 disk 4, o:1, dev:sda2
 disk 5, o:1, dev:sdb2
 disk 6, o:1, dev:sdc2
 disk 7, o:1, dev:sdd2
 disk 8, o:1, dev:sde2
 disk 9, o:1, dev:sdf2
 disk 10, o:1, dev:sdg2
 disk 11, o:1, dev:sdh2
md: syncing RAID array md1
md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc.
md: using maximum available idle IO bandwidth (but not more than 200000
KB/sec) for reconstruction.
md: using 128k window, over a total of 195357696 blocks.

5. The question

Why shows sdh2 as spare?
The MD array size is correct.
And i really can see, the all drive is reading, and sdh2 is *ONLY* writing.

Cheers,

Janos

(Happy new year! :)

Re: where is the spare drive? :-)

[Marc]

On Mon, 2 Jan 2006 00:26:58 +0100, JaniD++ wrote
> Hello, list,
> 
> I found something interesting when i try to create a brand new array 
> on brand new drives....
> 

<snip>

> 5. The question
> 
> Why shows sdh2 as spare?
> The MD array size is correct.
> And i really can see, the all drive is reading, and sdh2 is *ONLY* writing.
> 

I'm not 100% sure but from a post by Neil a while a go on the list, the spare
device is a temporary construct created during the resync operation. Once the
resync is complete it should disappear. 

You could try searching the list archives for the post - choice of keywords is
up to you ;)

Regards,
Marc

Re: where is the spare drive? :-)

[JaniD++]

----- Original Message ----- 
From: "Marc" <linux-raid@liquid-nexus.net>
To: "JaniD++" <djani22@dynamicweb.hu>; <linux-raid@vger.kernel.org>
Sent: Thursday, January 05, 2006 7:16 AM
Subject: Re: where is the spare drive? :-)


> On Mon, 2 Jan 2006 00:26:58 +0100, JaniD++ wrote
> > Hello, list,
> >
> > I found something interesting when i try to create a brand new array
> > on brand new drives....
> >
>
> <snip>
>
> > 5. The question
> >
> > Why shows sdh2 as spare?
> > The MD array size is correct.
> > And i really can see, the all drive is reading, and sdh2 is *ONLY*
writing.
> >
>
> I'm not 100% sure but from a post by Neil a while a go on the list, the
spare
> device is a temporary construct created during the resync operation. Once
the
> resync is complete it should disappear.
>
> You could try searching the list archives for the post - choice of
keywords is
> up to you ;)

Thanks, but i have found the bug already. ;-)

If i create new raid5, it should only parity resyncing, and not spare
rebuilding!

This happens, only if i use mdadm.
With raidtools works fine.

My problem is now the bitmap. :(
Only mdadm supports this....

Cheers,
Janos

>
> Regards,
> Marc
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
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Re: where is the spare drive? :-)

[Neil Brown]

On Monday January 2, djani22@dynamicweb.hu wrote:
> 
> 5. The question
> 
> Why shows sdh2 as spare?
> The MD array size is correct.
> And i really can see, the all drive is reading, and sdh2 is *ONLY* writing.
> 

 man mdadm

Towards the end of the CREATE MODE section:

       When creating a RAID5 array, mdadm will automatically create a degraded
       array with an extra spare drive.  This is because  building  the  spare
       into a degraded array is in general faster than resyncing the parity on
       a non-degraded, but not clean, array.  This feature can be  over-ridden
       with the --force option.


I hope this clarifies the situation.

NeilBrown

Re: where is the spare drive? :-)

[JaniD++]

----- Original Message ----- 
From: "Neil Brown" <neilb@suse.de>
To: "JaniD++" <djani22@dynamicweb.hu>
Cc: <linux-raid@vger.kernel.org>
Sent: Thursday, January 12, 2006 4:07 AM
Subject: Re: where is the spare drive? :-)


> On Monday January 2, djani22@dynamicweb.hu wrote:
> >
> > 5. The question
> >
> > Why shows sdh2 as spare?
> > The MD array size is correct.
> > And i really can see, the all drive is reading, and sdh2 is *ONLY*
writing.
> >
>
>  man mdadm
>
> Towards the end of the CREATE MODE section:
>
>        When creating a RAID5 array, mdadm will automatically create a
degraded
>        array with an extra spare drive.  This is because  building  the
spare
>        into a degraded array is in general faster than resyncing the
parity on
>        a non-degraded, but not clean, array.  This feature can be
over-ridden
>        with the --force option.
>
>
> I hope this clarifies the situation.
>
> NeilBrown

Ahh, this was avoid my attention.
The mdadm man page (and functionallity) is quite large.

I think this is more important to let some people to overwrite own data.
I think it is neccessary to place some note to the man page to warn people
about this exception.

Anyway this is a good idea! :-)

Thanks to note me about this.

Cheers,
Janos

>
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