mdadm can't reshape/resize arrays

mdadm can't reshape/resize arrays

[Goswin von Brederlow]

Hi,

I'm trying to resize/reshape some of my arrays:

md1 : active raid1 sdc5[1]
      9767424 blocks [2/1] [_U]
      bitmap: 48/150 pages [192KB], 32KB chunk

% mdadm --grow --size max /dev/md1
mdadm: Cannot set device size for /dev/md1: Device or resource busy

and dmesg says:
  md: couldn't update array info. -16


md2 : active raid5 sdc2[6](S) sde2[3] sdg1[1] sdf3[4] sdd1[5] sdb1[2]
sda1[0]
      945625280 blocks level 5, 64k chunk, algorithm 2 [6/6] [UUUUUU]
      bitmap: 0/181 pages [0KB], 512KB chunk

% mdadm --grow -n 7 /dev/md2 
mdadm: Need to backup 1920K of critical section..
mdadm: Cannot set device size/shape for /dev/md2: Device or resource busy

and dmesg says:
  md: couldn't update array info. -16


% uname -a
Linux frosties 2.6.29.4-frosties-1 #8 Sun Jun 7 00:48:55 CEST 2009 x86_64 GNU/Linux

% mdadm --version
mdadm - v2.6.9 - 10th March 2009


Anyone have an idea what is wrong there?

MfG
        Goswin

Re: mdadm can't reshape/resize arrays

[NeilBrown]

On Thu, June 25, 2009 1:03 am, Goswin von Brederlow wrote:
> Hi,
>
> I'm trying to resize/reshape some of my arrays:
>
> md1 : active raid1 sdc5[1]
>       9767424 blocks [2/1] [_U]
>       bitmap: 48/150 pages [192KB], 32KB chunk
>
> % mdadm --grow --size max /dev/md1
> mdadm: Cannot set device size for /dev/md1: Device or resource busy
>
> and dmesg says:
>   md: couldn't update array info. -16
>
>
> md2 : active raid5 sdc2[6](S) sde2[3] sdg1[1] sdf3[4] sdd1[5] sdb1[2]
> sda1[0]
>       945625280 blocks level 5, 64k chunk, algorithm 2 [6/6] [UUUUUU]
>       bitmap: 0/181 pages [0KB], 512KB chunk
>
> % mdadm --grow -n 7 /dev/md2
> mdadm: Need to backup 1920K of critical section..
> mdadm: Cannot set device size/shape for /dev/md2: Device or resource busy
>
> and dmesg says:
>   md: couldn't update array info. -16
>
>
> % uname -a
> Linux frosties 2.6.29.4-frosties-1 #8 Sun Jun 7 00:48:55 CEST 2009 x86_64
> GNU/Linux
>
> % mdadm --version
> mdadm - v2.6.9 - 10th March 2009
>
>
> Anyone have an idea what is wrong there?

md cannot grow arrays with bitmaps as it is not able to grow the bitmap.
You need to remove the bitmap, grow the array, then add the bitmap.
And unfortunately you cannot add the bitmap until the grow
has finished.

Yes, there is room for improvement here.

NeilBrown

Re: mdadm can't reshape/resize arrays

[Goswin von Brederlow]

"NeilBrown" <neilb@suse.de> writes:

> On Thu, June 25, 2009 1:03 am, Goswin von Brederlow wrote:
>> Hi,
>>
>> I'm trying to resize/reshape some of my arrays:
>>
>> md1 : active raid1 sdc5[1]
>>       9767424 blocks [2/1] [_U]
>>       bitmap: 48/150 pages [192KB], 32KB chunk
>>
>> % mdadm --grow --size max /dev/md1
>> mdadm: Cannot set device size for /dev/md1: Device or resource busy
>>
>> and dmesg says:
>>   md: couldn't update array info. -16
>>
>>
>> md2 : active raid5 sdc2[6](S) sde2[3] sdg1[1] sdf3[4] sdd1[5] sdb1[2]
>> sda1[0]
>>       945625280 blocks level 5, 64k chunk, algorithm 2 [6/6] [UUUUUU]
>>       bitmap: 0/181 pages [0KB], 512KB chunk
>>
>> % mdadm --grow -n 7 /dev/md2
>> mdadm: Need to backup 1920K of critical section..
>> mdadm: Cannot set device size/shape for /dev/md2: Device or resource busy
>>
>> and dmesg says:
>>   md: couldn't update array info. -16
>>
>>
>> % uname -a
>> Linux frosties 2.6.29.4-frosties-1 #8 Sun Jun 7 00:48:55 CEST 2009 x86_64
>> GNU/Linux
>>
>> % mdadm --version
>> mdadm - v2.6.9 - 10th March 2009
>>
>>
>> Anyone have an idea what is wrong there?
>
> md cannot grow arrays with bitmaps as it is not able to grow the bitmap.
> You need to remove the bitmap, grow the array, then add the bitmap.
> And unfortunately you cannot add the bitmap until the grow
> has finished.
>
> Yes, there is room for improvement here.
>
> NeilBrown

Most notably that mdadm catches that and gives a sensible error.

Thanks.

MfG
        Goswin