Re: Raid 10 Issue [SOLVED]

[Stefan Lamby <webmaster@peter-speer.de>]

> Robin Hill <robin@robinhill.me.uk> hat am 6. März 2015 um 09:54 geschrieben:
>
>
> On Thu Mar 05, 2015 at 06:56:00PM +0100, Stefan Lamby wrote:
>
> > Hello List.
> >
> > I was setting up a new machine using ubuntu 14.04.02 lts using its
> > installer,
> > configuring a raid 10 with 2 disks and lvm on top of it. I was using 2 disks
> > and
> > now I like to add 2 more disks to the array so i want to end up with 4
> > disks, no
> > spare.
> >
> > Searching the internet I found that I am not able to --grow the array with
> > the
> > mdadm version this ubuntu is using (v3.2.5).
> > Is that right?
> >
> > So I decided to build a new array that way and try to move my data
> > afterwards,
> > which failed:
> > (Is it OK to do it that way or do you recommend another?)
> >
> > root@kvm15:~# mdadm --verbose --create --level=10 --raid-devices=4 /dev/md10
> > missing missing /dev/sdc1 /dev/sdd1
> > mdadm: layout defaults to n2
> > mdadm: layout defaults to n2
> > mdadm: chunk size defaults to 512K
> > mdadm: /dev/sdc1 appears to be part of a raid array:
> > level=raid10 devices=4 ctime=Fri Feb 27 15:49:14 2015
> > mdadm: /dev/sdd1 appears to be part of a raid array:
> > level=raid10 devices=4 ctime=Fri Feb 27 15:49:14 2015
> > mdadm: size set to 1904165376K
> > Continue creating array? y
> > mdadm: Defaulting to version 1.2 metadata
> > mdadm: RUN_ARRAY failed: Input/output error
> > <<<<<<<<<<<<<<<<<<<<<<<<<<<
> > root@kvm15:~#
> >
> IIRC, in a RAID10 setup, the redundant pair is held on adjacent drives.
> You've specified two adjacent drives as missing, so the array cannot be
> run. Try doing:
> mdadm --verbose --create --level=10 --raid-devices=4 /dev/md10 \
> missing /dev/sdc1 missing /dev/sdd1
>

Dang!
One shot one catch, thank you so much!

Dear Maintainer,
please take a one-to-one copy of Robins explaination and print it if another
dumb user like me tries to do the same and is caught also. This could help avoid
a lot of frustration. There are posts in the internet which claim the order of
the given devices is critical.

Thank you all for taking the time to help.
Stefan
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