Re: IMSM Raid 5 always read only and gone after reboot

[Iwan Zarembo <iwan@zarembo.de>]

> It sounds like mdmon is not being started.
> mdmon monitors the array and performs any metadata updates required.
>
> The reason mktable is taking more than a second is that it tries to write to
> the array, the kernel marks the array as 'write-pending' and waits for mdmon
> to notice, update the metadata, and switch the array to 'active'.  But mdmon
> never does that.
>
> mdmon should be started by mdadm but just to check you can start it by hand:
>
>   /sbin/mdmon md126
> or
>   /sbin/mdmon --all
>
> If this makes it work, you need to work out why mdmon isn't being started.
>
> NeilBrown
>
Hello NeilBrown,
I finally found it. I was using mdadm 3.1.4, it is in the repository of 
ubuntu. This version does not really support IMSM that this is the real 
problem. I found it because I did not have mdmon. It does not exists in 
this old version. So I downloaded the latest official relesae 3.2.1 and 
installed it via make && sudo make install. Now everything works 
perfectly. The array is available after reboot and the synchronization 
process works over BIOS and not over mdadm itself.
I would never found out that the version is making the trouble without 
your comment about mdmon. Thank you.

@Daniel,linbloke: Also a big thank you to you both. I learned a lot 
about raid with this problem.

Cheers,

Iwan