upgrading the superblock version

upgrading the superblock version

[Vasco Névoa]

Hello.

I'd like to know if it is possible to upgrade the superblock model  
version of an array, from 0.9 to 1.0 for example.

Theoretically it should be possible, I think. What would be the safe  
steps to do it?

I imagine something like:
- zeroing the current superblocks in all the array disks;
- (optionally) assembling the array in "build" mode, ignoring superblocks;
- updating the superblocks using the desired version.

If that isn't possible, then:
- zeroing the current superblocks in all the array disks;
- creating a new array with those disks, using the desired superblock  
version and --assume-clean;
- would this lead to the loss of the partition table inside the array?

Has anyone done such a thing?
How should I proceed?

Thanks,
Vasco.

Re: upgrading the superblock version

[Vasco Névoa]

I have read success reports that using "--create" on an array that  
already exists should preserve the disk data.
So to upgrade the superblock version one can simply do a --create with  
newer version requested?

What exactly happens to the partition and filesystem on the disk when  
one does mdadm --create or --zero-superblock?
Does it get altered at all?


Citando Vasco Névoa <vasco.nevoa@sapo.pt>:

>
> Hello.
>
> I'd like to know if it is possible to upgrade the superblock model  
> version of an array, from 0.9 to 1.0 for example.
>
> Theoretically it should be possible, I think. What would be the safe  
> steps to do it?
>
> I imagine something like:
> - zeroing the current superblocks in all the array disks;
> - (optionally) assembling the array in "build" mode, ignoring superblocks;
> - updating the superblocks using the desired version.
>
> If that isn't possible, then:
> - zeroing the current superblocks in all the array disks;
> - creating a new array with those disks, using the desired  
> superblock version and --assume-clean;
> - would this lead to the loss of the partition table inside the array?
>
> Has anyone done such a thing?
> How should I proceed?
>
> Thanks,
> Vasco.
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Re: upgrading the superblock version

[Simon Matthews]

Vasco,

2011/7/21 Vasco Névoa <vasco.nevoa@sapo.pt>:
>
> Hello.
>
> I'd like to know if it is possible to upgrade the superblock model version
> of an array, from 0.9 to 1.0 for example.

See the discussion with the subject  "Can't start array and Negative
"Used Dev Size" in this mailing list. You will see that I was advised
to do this very thing and given instructions on how to do it. 0.9 to
1.0 is possible, but not to 1.1 or 1.2

Simon
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