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FromNeil Brown <>
DateThu, 17 May 2007 15:03:31 +1000
SubjectRE: Software raid0 will crash the file-system, when each disk is 5TB
On Wednesday May 16, david@lang.hm wrote:
> On Thu, 17 May 2007, Neil Brown wrote:> > > On Thursday May 17, Jeff.Zheng@endace.com wrote:> >>> >>> The only difference of any significance between the working
> >>> and non-working configurations is that in the non-working,
> >>> the component devices are larger than 2Gig, and hence have
> >>> sector offsets greater than 32 bits.> >>> >> Do u mean 2T here?, but in both configuartion, the component devices are
> >> larger than 2T (2.25T&5.5T).> >> > Yes, I meant 2T, and yes, the components are always over 2T.> > 2T decimal or 2T binary?> 

Either.  The smallest as actually 2.75T (typo above).
Precisely it was
  2929641472  kilobytes
or 
  5859282944 sectors
or 
  0x15D3D9000 sectors.

So it is over 32bits already...

Uhm, I just noticed something.
'chunk' is unsigned long, and when it gets shifted up, we might lose
bits.  That could still happen with the 4*2.75T arrangement, but is
much more likely in the 2*5.5T arrangement.

Jeff, can you try this patch?

Thanks.
NeilBrown


Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
 ./drivers/md/raid0.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff .prev/drivers/md/raid0.c ./drivers/md/raid0.c
--- .prev/drivers/md/raid0.c	2007-05-17 10:33:30.000000000 +1000
+++ ./drivers/md/raid0.c	2007-05-17 15:02:15.000000000 +1000
@@ -475,7 +475,7 @@ static int raid0_make_request (request_q
 		x = block >> chunksize_bits;
 		tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
 	}
-	rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
+	rsect = ((((sector_t)chunk << chunksize_bits) + zone->dev_offset)<<1)
 		+ sect_in_chunk;
  
 	bio->bi_bdev = tmp_dev->bdev;
-
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