[dm-devel] RFC for multipath queue_if_no_path timeout.

[Mike Snitzer]

On Thu, Sep 26 2013 at  7:22pm -0400,
Alasdair G Kergon <agk at redhat.com> wrote:

> On Thu, Sep 26, 2013 at 10:47:13AM -0700, Frank Mayhar wrote:
> > Launching it from ramdisk won't help, particularly, since it still goes
> > through the block layer.  The other stuff won't help if a (potentially
> > unrelated) bug in the daemon happens to be being tickled at the same
> > time, or if some dependency happens to be broken and _that's_ what's
> > preventing the daemon from making progress.
>  
> Then put more effort into debugging your daemon so it doesn't have
> bugs that make it die?  Implement the timeout in a robust independent
> daemon if it's other code there that's unreliable?
> 
> > And as far as lvm2 and multipath-tools, yeah, they cope okay in the kind
> > of environments most people have, but that's not the kind of environment
> > (or scale) we have to deal with.
> 
> In what way are your requirements so different that a locked-into-memory
> monitoring daemon cannot implement this timeout?

Frank, I had a look at your patch.  It leaves a lot to be desired, I was
starting to clean it up but ultimately found myself agreeing with
Alasdair's original point: that this policy should be implemented in the
userspace daemon.

Mike