raid5 - adding journal to an existing device?

raid5 - adding journal to an existing device?

[Tomasz Chmielewski]

mdadm manual specifies the following for create, build and grow modes:

        --write-journal
               Specify journal device for the RAID-4/5/6 array.

However:

# mdadm --grow /dev/md2 --write-journal /dev/sdc1
mdadm: :option --write-journal not valid in grow mode


Is it not yet supported, will never be supported, or am I simply trying 
to use it in a  wrong way?



Tried the following versions:

# ./mdadm -V
mdadm - v3.4-115-ge22fe3a - 29th November 2016

# mdadm -V
mdadm - v3.4 - 28th January 2016


Tomasz Chmielewski
https://lxadm.com

Re: raid5 - adding journal to an existing device?

[Shaohua Li]

On Sat, Feb 25, 2017 at 11:12:21PM +0900, Tomasz Chmielewski wrote:
> mdadm manual specifies the following for create, build and grow modes:
> 
>        --write-journal
>               Specify journal device for the RAID-4/5/6 array.
> 
> However:
> 
> # mdadm --grow /dev/md2 --write-journal /dev/sdc1
> mdadm: :option --write-journal not valid in grow mode
> 
> 
> Is it not yet supported, will never be supported, or am I simply trying to
> use it in a  wrong way?
> 
> 
> 
> Tried the following versions:
> 
> # ./mdadm -V
> mdadm - v3.4-115-ge22fe3a - 29th November 2016
> 
> # mdadm -V
> mdadm - v3.4 - 28th January 2016

Cc: Song and Jes.

I think we support hotadd journal. Will let Song clarify.

Thanks,
Shaohua

Re: raid5 - adding journal to an existing device?

[Song Liu]

> On Mar 2, 2017, at 10:39 AM, Shaohua Li <shli@kernel.org> wrote:
> 
> On Sat, Feb 25, 2017 at 11:12:21PM +0900, Tomasz Chmielewski wrote:
>> mdadm manual specifies the following for create, build and grow modes:
>> 
>>       --write-journal
>>              Specify journal device for the RAID-4/5/6 array.
>> 
>> However:
>> 
>> # mdadm --grow /dev/md2 --write-journal /dev/sdc1
>> mdadm: :option --write-journal not valid in grow mode
>> 
>> 
>> Is it not yet supported, will never be supported, or am I simply trying to
>> use it in a  wrong way?
>> 
>> 
>> 
>> Tried the following versions:
>> 
>> # ./mdadm -V
>> mdadm - v3.4-115-ge22fe3a - 29th November 2016
>> 
>> # mdadm -V
>> mdadm - v3.4 - 28th January 2016
> 
> Cc: Song and Jes.
> 
> I think we support hotadd journal. Will let Song clarify.
> 
> Thanks,
> Shaohua

We have support for hotadd journal to an array with broken/missing journal. 
We haven't implement hotted journal to arrays with no journal ever. We do plan
to add the feature. 

Thanks,
Song