Adding journal to existing raid5 arrary

Adding journal to existing raid5 arrary

[Maarten van Malland]

I was trying to add a previously created raid5 array with:

mdadm --add-journal /dev/md3 /dev/sdc

That gave an error though: "/dev/md3 does not support journal device
/dev/sdc". I'm guessing that happens because the initial array was created
without journal support? Is there anything I can do to get this to work
without recreating the entire array?

Re: Adding journal to existing raid5 arrary

[Song Liu]

Currently, --add-journal does not support adding journal to an existing array,
We plan to add that soon.

Song

Re: Adding journal to existing raid5 arrary

[Maarten van Malland]

Well that explains that then :-). Is it also planned to support
removal of the journal device? I can imagine that there are cases
(such as performance issues) that you would like to revert to the old
situation...

On Wed, Aug 17, 2016 at 11:46 PM, Song Liu <songliubraving@fb.com> wrote:
> Currently, --add-journal does not support adding journal to an existing array,
> We plan to add that soon.
>
> Song
>

Re: Adding journal to existing raid5 arrary

[Song Liu]

Yes, we do plan to add removal as well. 
 
Thanks,
Song

>> On 8/18/16, 12:51 AM, "Maarten van Malland" <maartenvanmalland@gmail.com> wrote:

    Well that explains that then :-). Is it also planned to support
    removal of the journal device? I can imagine that there are cases
    (such as performance issues) that you would like to revert to the old
    situation...
    
    On Wed, Aug 17, 2016 at 11:46 PM, Song Liu <songliubraving@fb.com> wrote:
    > Currently, --add-journal does not support adding journal to an existing array,
    > We plan to add that soon.
    >
    > Song
    >
    

Re: Adding journal to existing raid5 arrary

[Maarten van Malland]

I was wondering if this is now possible to do with kernel 4.11? It's
not completely clear to me from the release notes.

Thank you,

Maarten

On Thu, Aug 18, 2016 at 6:03 PM, Song Liu <songliubraving@fb.com> wrote:
> Yes, we do plan to add removal as well.
>
> Thanks,
> Song
>
>>> On 8/18/16, 12:51 AM, "Maarten van Malland" <maartenvanmalland@gmail.com> wrote:
>
>     Well that explains that then :-). Is it also planned to support
>     removal of the journal device? I can imagine that there are cases
>     (such as performance issues) that you would like to revert to the old
>     situation...
>
>     On Wed, Aug 17, 2016 at 11:46 PM, Song Liu <songliubraving@fb.com> wrote:
>     > Currently, --add-journal does not support adding journal to an existing array,
>     > We plan to add that soon.
>     >
>     > Song
>     >
>
>