Bug#618463: mdadm: Mdadm grow of Raid1 destroys metadata

[martin f krafft]

also sprach NeilBrown <neilb at suse.de> [2011.03.18.0329 +0100]:
> > Commands where as following:
> > lvextend -L +10G vda/opt
> > lvextend -L +10G vdb/opt
> 
> md was not made aware of these changes to the sizes of the individual devices,
> so
> 
> > mdadm --grow /dev/md2 --size=max
> 
> This caused mdadm to do nothing as it always "knew" that all of
> the available space on the devices was already in use.

Hello Neil,

thanks for your time taken to reply to this bug report!

I just want to point out that I understand Michael, and the
behaviour is strange to people who work with LVM a lot. For
instance, if vda/opt had a filesystem on it, then after extending
the LV, I could just grow the filesystem to maximum size. That's
because it does not "know that all of the space is already in use",
but because it checks the size of the device and of itself and then
acts if they differ. mdadm should probably do the same, don't you
think? I.e. --grow --size=max should cause it to (re-)check if there
is available space, and then act accordingly.

Best regards,

-- 
 .''`.   martin f. krafft <madduck at d.o>      Related projects:
: :'  :  proud Debian developer               http://debiansystem.info
`. `'`   http://people.debian.org/~madduck    http://vcs-pkg.org
  `-  Debian - when you have better things to do than fixing systems
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