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Re: Xfs Access to block zero exception and system crash

To: Sagar Borikar <sagar_borikar@xxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
Subject: Re: Xfs Access to block zero exception and system crash
From: Sagar Borikar <sagar_borikar@xxxxxxxxxxxxxx>
Date: Wed, 02 Jul 2008 09:48:46 +0530
In-reply-to: <20080701064437.GR29319@disturbed>
Organization: PMC Sierra Inc
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Dave Chinner wrote:
On Mon, Jun 30, 2008 at 03:54:44PM +0530, Sagar Borikar wrote:
After running my test for 20 min, when I check the fragmentation status of file system, I observe that it
is severely fragmented.

Depends on your definition of fragmentation....

[root@NAS001ee5ab9c85 ~]# xfs_db -c frag -r /dev/RAIDA/vol
actual 94343, ideal 107, fragmentation factor 99.89%

And that one is a bad one ;)

Still, there are a lot of extents - ~1000 to a file - which
will be stressing the btree extent format code.

Do you think, this can cause the issue?

Sure - just like any other workload that generates enough
extents. Like I said originally, we've fixed so many problems
in this code since 2.6.18 I'd suggest that your only sane
hope for us to help you track done the problem is to upgrade
to a current kernel and go from there....

Cheers,,

Dave.
Thanks again Dave. But we can't upgrade the kernel as it is already in production and on field. So do you think, periodic cleaning of file system using xfs_fsr can solve the issue? If not, could you kindly direct me what all patches were fixing similar problem? I can try back porting them.

Thanks
Sagar


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