Re: userspace block driver?

Jeff Garzik
2005-11-09T08:01:48Z

Jens Axboe wrote:
> On Wed, Nov 09 2005, Jeff Garzik wrote:
>
>>Neil Brown wrote:
>>
>>>On Wednesday November 9, jgarzik@pobox.com wrote:
>>>
>>>
>>>>Has anybody put any thought towards how a userspace block driver
>>>>would work?
>>>
>>>
>>>Isn't this was enbd does?
>>> http://www.it.uc3m.es/~ptb/nbd/
>>
>>Is there something there relevant for modern kernels? I would sure hope
>>I could come up with something more lightweight than that.
>
>
> I was going to say drbd, but then you did say more lightweight :-)
>
> Is nbd completely screwed these days?

nbd does more than I want.

_All_ that is needed is flipping requests <somehow> to/from userspace.
nbd messes directly with sockets and such, which I don't want. It does
way too much, hardcodes way too much.

loop is a closer model to a generic userspace block device than nbd, I
think.

Though, answering your question directly, I do get the impression that
in-kernel nbd has been left behind in favor of drbd and enbd, out in the
few places where nbd-ish solutions are used.

Jeff