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

Patrick Mansfield
2002-09-10T19:37:32Z

On Tue, Sep 10, 2002 at 12:00:47PM -0700, Patrick Mochel wrote:
>
> On Tue, 10 Sep 2002, Patrick Mansfield wrote:
>
> > On Tue, Sep 10, 2002 at 10:21:53AM -0700, Patrick Mochel wrote:
> > > 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.
>
> Which is it that you want? One canonical name or all the paths? I supplied
> a solution for the former in my repsonse. The latter is solved via the
> exposure of the paths in driverfs, which has been discussed previously.
>
>
> -pat

For scsi multi-path, one name; without scsi multi-path (or for individual
paths that are not exposed in driverfs) each path probably needs to show up
in user space with a different name so md or other volume managers can use
them.

-- Patrick Mansfield