Re: [RFC] Multi-path IO in 2.5/2.6 ?

Patrick Mansfield
2002-09-10T18:42:57Z

On Tue, Sep 10, 2002 at 10:21:53AM -0700, Patrick Mochel wrote:
>
> > > > Generic device naming consistency is a problem if multiple devices
> > > > show up with the same id.
> > >
> > > Patrick Mochel has an open task to come up with a solution to this.
> >
> > I don't think this can be solved if multiple devices show up with the same
> > id. If I have five disks that all say I'm disk X, how can there be one
> > name or handle for it from user level?
>
> Easy: you map the unique identifier of the device to a name in userspace.
> In our utopian future, /sbin/hotplug is called with that unique ID as one
> of its parameters. It searches for, and finds names based on the ID is. If
> the name(s) already exist, then it doesn't continue.
>
>
> -pat

But then if the md or volume manager wants to do multi-path IO it
will not be able to find all of the names in userspace since the
extra ones (second path and on) have been dropped.

-- Patrick Mansfield