Re: [patch 4/5] fail-injection capability for disk IO

From: Ric Wheeler
Date: Wed Aug 23 2006 - 15:40:56 EST

Mario 'BitKoenig' Holbe wrote:
Jens Axboe <axboe@xxxxxxx> wrote:

On Wed, Aug 23 2006, Andi Kleen wrote:

I think I would prefer a stackable driver instead of this hook.

I second this, preferrably a device-mapper target similar to dm-error.

But that makes it more tricky to setup a test, since you have to change
from using /dev/sda (for example) to /dev/stacked-driver.

Do you really think somebody would run such tests on otherwise normally
used devices?

We certainly run this kind of tests on a routine basis - before we ship a kernel to our installed field, we need to verify that it will handle disk IO errors correctly.

In our case, the tests are run on a farm of machines that get pxe'ed to a specific image, tested (usually by sticking in a disk known to be bad enough to cause reliable errors ;-)) and then we watch to see that the errors do not cause hangs, etc.

Having a requirement to change our standard image (sda -> stacked-driver) would not be impossible, but would be less convenient...

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