Using a newer mdadm version just for re-adding a device

Using a newer mdadm version just for re-adding a device

[Sven Hartrumpf]

Hello.

Is it safe to mix mdadm versions in the following scenario?

openSUSE 12.1 comes with mdadm 3.2.2 (and kernel 3.1), which works fine
except that I am hit by the re-add bug:
I removed a partition (after "mdadm --manage --set-faulty ...") from a perfectly
working /dev/md1, but re-adding with "mdadm /dev/md1 -a ..." fails.
Reading the mailing list and the Changelog, I understand that
this is fixed in mdadm 3.2.5.
Hence, I compiled mdadm 3.2.5 from source.

Now my question is:
Can I safely use the resulting binary (renamed to mdadm325 to avoid confusion)
to re-add the device and then continue to use the 3.2.2 package from openSUSE?

Thanks for reading
Sven

Re: Using a newer mdadm version just for re-adding a device

[Sven Hartrumpf]

To answer my own question (about a RAID-1):

Wed, 30 May 2012 19:38:15 +0200 (CEST), I wrote:
> Is it safe to mix mdadm versions in the following scenario?
...
> Now my question is:
> Can I safely use the resulting binary (renamed to mdadm325 to avoid confusion)
> to re-add the device and then continue to use the 3.2.2 package from openSUSE?

I made a backup and tried the above: it worked perfectly.

Sven

Re: Using a newer mdadm version just for re-adding a device

[NeilBrown]

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On Thu, 31 May 2012 19:24:14 +0200 (CEST) Sven Hartrumpf <hartrumpf@gmx.net>
wrote:

> To answer my own question (about a RAID-1):
> 
> Wed, 30 May 2012 19:38:15 +0200 (CEST), I wrote:
> > Is it safe to mix mdadm versions in the following scenario?
> ...
> > Now my question is:
> > Can I safely use the resulting binary (renamed to mdadm325 to avoid confusion)
> > to re-add the device and then continue to use the 3.2.2 package from openSUSE?
> 
> I made a backup and tried the above: it worked perfectly.

I like it when people work out the answer themselves :-)

The only possible issue is that when 3.2.5 adds a new device it will try to
give it a larger "Data Offset".  This won't confuse md, but it might confuse
you in later life.

About the only time you need to ensure you have a consistent version of mdadm
is when re-creating an array that died in some way and you want to recover
the data off it, but "-assemble --force" doesn't work.

NeilBrown


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