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Date: Wed, 20 Apr 2016 13:50:36 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] I/O errors reported to guest for raw-image-file
 backed /dev/vda - but host sees no I/O errors
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To: Fam Zheng <famz@redhat.com>
Cc: Lutz Vieweg <lvml@5t9.de>, qemu-devel@nongnu.org, qemu-block@nongnu.org

Am 20.04.2016 um 04:11 hat Fam Zheng geschrieben:
> On Tue, 04/19 19:47, Lutz Vieweg wrote:
> > The guest drive parameters are:
> > > -drive "file=image.raw,if=virtio,format=raw,media=disk,cache=unsafe,werror=report,rerror=report"
> 
> Given this implies aio=threads...
> 
> > Can you provide any hint on how to pursue the cause of these errors?
> > (I thought about using "strace -f -p ..." on qemu, but I don't
> > know what exactly to look for in the output - some failed "pwrite()"
> > to the image file?)
> 
> ... yes, this should work.

To catch all possible write failures, I think pwrite, pwritev and
possibly fdatasync need to be considered.

Kevin