migrate to bad block list

migrate to bad block list

[Michael Ryan]

Is there any way to migrate an existing array created with mdadm v3.2.5 and using 1.1 metadata to use a bad block list?  I'm assuming not as there wouldn't be space reserved for the list, but I need to ask.

Thanks for your response!

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Re: migrate to bad block list

[NeilBrown]

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On Wed, 15 Oct 2014 17:18:19 +0000 Michael Ryan <mryan@lenovoemc.com> wrote:

> 
> Is there any way to migrate an existing array created with mdadm v3.2.5 and using 1.1 metadata to use a bad block list?  I'm assuming not as there wouldn't be space reserved for the list, but I need to ask.
> 
> Thanks for your response!

mdadm tends to leave a fair bit of unused space on devices so that things
like a bad block list can easily be added.
If you can stop the array, then do that and re-assemble with
  --update=bbl

and you should  get a bbl added to each device.

If you cannot stop the array, but it has a bitmap, then
you can, for each device:

  mdadm /dev/mdX --fail /dev/adevice
  mdadm /dev/mdX --remove /dev/adevice
  mdadm /dev/mdX --re-add --update=bbl /dev/adevice

I think that should work.  The "bblk" is a feature of the device, not of the
whole array.  So you can add it to each device.

I haven't actually tested the above I think, so it might be safest to make an
array with loop-back devices and experiment.

NeilBrown

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Re: migrate to bad block list

[Piergiorgio Sartor]

Hi Neil,

On Thu, Oct 16, 2014 at 05:54:14PM +1100, NeilBrown wrote:
> On Wed, 15 Oct 2014 17:18:19 +0000 Michael Ryan <mryan@lenovoemc.com> wrote:
> 
> > 
> > Is there any way to migrate an existing array created with mdadm v3.2.5 and using 1.1 metadata to use a bad block list?  I'm assuming not as there wouldn't be space reserved for the list, but I need to ask.
> > 
> > Thanks for your response!
> 
> mdadm tends to leave a fair bit of unused space on devices so that things
> like a bad block list can easily be added.
> If you can stop the array, then do that and re-assemble with
>   --update=bbl
> 
> and you should  get a bbl added to each device.
> 
> If you cannot stop the array, but it has a bitmap, then
> you can, for each device:
> 
>   mdadm /dev/mdX --fail /dev/adevice
>   mdadm /dev/mdX --remove /dev/adevice
>   mdadm /dev/mdX --re-add --update=bbl /dev/adevice
> 
> I think that should work.  The "bblk" is a feature of the device, not of the
> whole array.  So you can add it to each device.

is there any technical reason why it is not
possible to enable/disable the bbl like the
write intent bitmap?
Something like:

mdadm --grow /dev/<md> --bbl=[internal|none]

Thanks,

bye,

pg

> I haven't actually tested the above I think, so it might be safest to make an
> array with loop-back devices and experiment.
> 
> NeilBrown



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piergiorgio
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