Re: mdadm --monitor: need extra feature?

[Sergiusz Brzeziński <Sergiusz.Brzezinski@xxxxxxxxxxxxxx>]

W dniu 22.08.2012 12:12, Adam Goryachev pisze:
> On 22/08/12 19:50, Sergiusz Brzeziński wrote:
> > 3. In Ubuntu there is in /lib/udev/rules.d/64-md-raid.rules file
> > responsible for this. I only changed one line:
> >
> > ACTION=="add", RUN+="/sbin/mdadm --incremental $tempnode"
> > to:
> > ACTION=="add", RUN+="/sbin/mdadm --incremental --run $tempnode"
> >
> > And thats all!
> >
> > Now, I don't have to use my script from crontab anymore. Raid start
> > rebuilding array immediately after disk is inserted.
> Could this cause a problem (ie, what is the reason this is not the
> default value)?
>
> My guess is it may cause md to start an array where all "available"
> disks are not yet added to the array. ie, if you are plugging in three
> drives, it might run the array after plugging in the second array, and
> then when you plugin the third drive it will need to do a resync.
>
> I suppose worst case is a resync where it wasn't really needed.
>
> Regards,
> Adam

I made a try.

1.
I never had before 3 drives at one time. After inserting the third drive for the 
first time (the drive had a raid partition with proper UUID) it happened 
nothing. (or maybye something happened but I don't know what because i turned 
off the debugging :( )

2.
Than I made mdadm /dev/md0 -a /dev/third_drive
It was added as a spare.

3.
I removed and inserted again the third drive. Again nothing. No info in log, and 
it was not added as a spare.

I don't know if it is good or wrong behawior (maybye the drive should appear 
automaticaly as a spare?) but for me it is not a problem because I don't use 
spares :)

best regards

Sergiusz
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