Re: Understanding raid array status: Active vs Clean

[NeilBrown <neilb@suse.de>]

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On Sat, 28 Jun 2014 05:01:00 +0200 George Duffield
<forumscollective@gmail.com> wrote:

> >> > changing the value to 0.500:
> >> > # echo 0.503 > /sys/block/md0/md/safe_mode_delay
> >> >
> >> > makes no difference to the array state.
> >
> > What if you write a smaller number?  e.g. 0.1
> 
> No change to array state.
> 
> > What does /sys/block/md0/md/array_state show?
> 
> Funnily enough, it shows Clean


Ahh - I found it.
In get_array_info() in drivers/md/md.c:

	if (mddev->in_sync)
		info.state = (1<<MD_SB_CLEAN);
	if (mddev->bitmap && mddev->bitmap_info.offset)
		info.state = (1<<MD_SB_BITMAP_PRESENT);


that last line should be "|=".

Because you have a bitmap, the 'clean' state is being hidden.

Though if you have a bitmap, the 'clean' state isn't really important because
the bitmap knows which regions are 'clean' and which are not.

But it should be fixed.  I'll send a patch next week.

Thanks for persisting.

NeilBrown

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