Re: raid is dangerous but that's secret (was Re: [patch] ext2/3:document conditions when reliable operation is possible)

[david]

On Sun, 30 Aug 2009, Pavel Machek wrote:

> > > From: Theodore Tso <tytso@xxxxxxx>
> > To use your ABS brakes analogy, just becase it's not safe to rely on
> > ABS brakes if the "check brakes" light is on, that doesn't justify
> > writing something alarmist which claims that ABS brakes don't work
> > 100% of the time, don't use ABS brakes, they're broken!!!!
>
> If it only was this simple. We don't have 'check brakes' (aka
> 'journalling ineffective') warning light. If we had that, I would not
> have problem.
>
> It is rather that your ABS brakes are ineffective if 'check engine'
> (RAID degraded) is lit. And yes, running with 'check engine' for
> extended periods may be bad idea, but I know people that do
> that... and I still hope their brakes work (and believe they should
> have won suit for damages should their ABS brakes fail).

the 'RAID degraded' warning says that _anything_ you put on that block 
device is at risk. it doesn't matter if you are using a filesystem with a 
journal, one without, or using the raw device directly.

David Lang
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