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

[Ric Wheeler <ric@emc.com>]

Mario 'BitKoenig' Holbe wrote:
> Jens Axboe <axboe@suse.de> 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...

ric