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Re: [Xen-devel] AFS-based VBD backend

On Thu, Dec 23, 2004 at 12:31:22PM -0000, Ian Pratt wrote:
>  > > The blocktap backend driver is what you want. I'm not sure of it's 
> > > current state, but the plan is to enable you to terminate a 
> > blk device 
> > > channel in user-space.
> > 
> > Cool!  Where was the most recent version of that?
> Unstable tree, but probably works in 2.0 too.

Thanks -- I'm going to look at it over the holidays.

> > I'm one of the folks who ran into the NFS root hangs early on 
> > -- trying very hard to get off of it, hence this messing 
> > about with alternatives.
> > Granted, I'm not using same-machine NFS, don't know how much 
> > that would reduce the hangs.
> Do you still see hangs with 2.6.9 kernels?

We're not on 2.6.x yet, due to lagging OpenAFS support.  I am seeing the
complaints about NFS roots in early 2.6 kernels though -- do you have
any reason to think it's better now than 2.4?

> > One variation on that theme that I have tested is an enbd 
> > server running on an AFS client, serving block devices to 
> > dom0 on another machine.  ;-) Slow, but seems stable.  
> > Haven't tried same-machine with that either, because it eats 
> > about 30% CPU on the enbd server under load.
> We use redhat gnbd in preference to enbd.

I noticed that.  You said something last October about running both the
gnbd client and server in dom0 on a number of machines -- I thought
importing from the same machine would cause a deadlock, so I've been
trying to figure out what you're actually doing.

Stephen G. Traugott  (KG6HDQ)
UNIX/Linux Infrastructure Architect, TerraLuna LLC
http://www.stevegt.com -- http://Infrastructures.Org

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