Re: [PATCH 1/3] nbd: support FLUSH requests

Alex Bligh
2013-02-13T00:00:19Z

Paolo,

On 12 Feb 2013, at 18:06, Paolo Bonzini wrote:

> Il 12/02/2013 18:37, Alex Bligh ha scritto:
>> For my education, why remove the FUA stuff?
>
> Because I had no way to test it.

I think my mods to the official NBD code support FUA (albeit not very efficiently)

>>>>>> Hmmm... the underlying storage could be md/dm RAIDs in which case FUA
>>>>>> should be cheaper than FLUSH.
>>>>
>>>> If someone ever wrote a virtio-blk backend that sits directly ontop
>>>> of the Linux block layer that would be true.
>> In this case we don't know what the backend is sitting on top of
>> a-priori. It might be the current nbd server code, but it might
>> not be.
>
> Do you know of any other NBD server than the "official" one and qemu-nbd?

Yes. I know one well (but it's not open source). NBD seems to be the 'goto protocol' for writing distributed block store drivers in user space.

--
Alex Bligh