Re: Hi! Strange issue with LSR -- bitmaps hadn't been used during 2 of 3 RAIDs resync

[NeilBrown <neilb@suse.de>]

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On Mon, 28 May 2012 00:10:33 +0800 Igor M Podlesny <for.poige+lsr@gmail.com>
wrote:

> On 27 May 2012 20:00, NeilBrown <neilb@suse.de> wrote:
> > On Sun, 27 May 2012 19:32:40 +0800 Igor M Podlesny <for.poige+lsr@gmail.com>
> > wrote:
> >>    A power outage has happened to system (which was in "suspend"
> >> state) with RAID-10, RAID-5 and RAID-6. Later on boot, RAID-10 was
> >> fast re-synced using bitmap, but both RAID-5 and RAID-6 were in
> >> auto-readonly mode with resync=DELAYED. When they flipped to
> >> Read-Write, LSR started re-syncing not using bitmaps seemingly. A bug?
> >
> > Maybe.  But with so little detail it is hard to say.
> > What made you think the bitmaps weren't being used?
> 
>    Well, it is reasonable to assume that host being put in suspend
> mode wouldn't have much not synced data at all. RAID-10 had been
> progressing its resync quite fast, it was obvious that it had been
> using bitmaps for that. Moreover — RAID-10 was the most I/O active
> comparing to others, AFAIR.

Unfortunately vague statements about "it was obvious" or "AFAIR" don't really
help in analysing a situation to find any bugs.
I can only really work with concrete facts.  Without them I cannot help.

> 
> > Did that arrays still have their bitmaps?
> 
>    I still have that RAID-6, yep:
> 
> md127 : active raid6 sdg5[2] sdf5[6] sde5[7] sda5[0] sdd5[3] sdc5[1]
>       1071984640 blocks super 1.0 level 6, 1024k chunk, algorithm 2
> [6/6] [UUUUUU]
>       bitmap: 0/1 pages [0KB], 131072KB chunk
> 
> > Where they degraded?
> 
>    No way.
> 
> > How many bits were set in the bitmaps (probably too late to check now)?
> 
>    Please see above. And the RAID-5 one was recently dismissed, alas.
> 
> > Is it reproducable ?  ... OK, I don't really expect you to try to reproduce
> > it, but if you could that would be awesome!
> 
>    Well, might be VirtualBox would allow for such kind of experiment, dunno. )
> 
>    P. s. Oh, and BTW, I see 2.6.18 supplied by RedHat still has the
> bug causing kernel panic when using WIB -- couldn't you please point
> out is it due to they're missing some important bugfix you made later?

I have no time or interest for submiting bug reports to distros that I don't
use.  If the presence of the bug concerns you, I suggest you report it.

NeilBrown


> 
> --


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