--assemble --scan --no-degrades assembles+run degraded RAID1?

--assemble --scan --no-degrades assembles+run degraded RAID1?

[Christoph Anton Mitterer]

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Hi.

This is just some minor thing I've noticed:

I intentionally degraded a 2-device RAID1,... and try to auto assemble
it via:
--assemble --scan --no-degrade

It seems this not only assembles the array but also runs it, at least I
can write to the /dev/md/foo file.

I'd have expected that this does not work... but it does...


Did I get anything wrong here?


Cheers,
Chris.

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Re: --assemble --scan --no-degrades assembles+run degraded RAID1?

[NeilBrown]

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On Sat, 20 Jul 2013 00:47:51 +0200 Christoph Anton Mitterer
<calestyo@scientia.net> wrote:

> Hi.
> 
> This is just some minor thing I've noticed:
> 
> I intentionally degraded a 2-device RAID1,... and try to auto assemble
> it via:
> --assemble --scan --no-degrade
> 
> It seems this not only assembles the array but also runs it, at least I
> can write to the /dev/md/foo file.
> 
> I'd have expected that this does not work... but it does...
> 
> 
> Did I get anything wrong here?

"--no-degraded" is a slight misnomer.  It should be
 "--no-degraded-unless-known-to-be-degraded".

The case that it stops is when you shut down the array with the array working
perfectly, remove a drive, the try to start the array up again.
In this case the array doesn't know that it is degraded, so "--no-degraded"
will stop it from being assembled.

This is useful when device discovery is slow or unreliable.

NeilBrown


> 
> 
> Cheers,
> Chris.


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