Re: [Qemu-devel] [PATCH] bdrv_flush error handling

[Avi Kivity <avi@qumranet.com>]

Paul Brook wrote:
>>> Finally, it would perhaps be best if the block device emulators wrote
>>> to the qemu console to complain if they give write errors.  Otherwise
>>> the errno value and other important information will be lost, which
>>> makes debugging hard.
>>>       
>> If by 'qemu console' you mean stderr, then fine, but please don't
>> spew log messages to the  monitor console, because that'll make it
>> very hard to interact with reliably from management tools.
>>     
>
> Actually I think a better default would be for qemu to die right there and 
> then.  If the host is getting IO errors then something is badly wrong, and 
> you're probably screwed anyway.
>   

If you're passing through a real disk or volume, this denies the guest 
the possibility of recover y (for example, if it is running a RAID setup 
over multiple volumes, or if you are testing the guest's ability to 
recover from errors).

For non-raw formats, you can pass through errors on data, but it is 
impossible to recover on metadata errors, so dying on I/O error should 
be fine.

-- 
Any sufficiently difficult bug is indistinguishable from a feature.