[dm-devel] [RFC] How to fix system stall on root volume multipath

[Christophe Varoqui]

Le vendredi 16 novembre 2007 à 09:41 +0100, Christophe Varoqui a écrit :
> > > Ben, Christophe,
> > > Is that code still problem for current multipathd?
> > > And what do you think about my proposal?
> > > 
> > I'm not found of yet-another user-visible ramfs for multipathd use,
> > that's why I started with the private namespace tricks. The problems are
> > still there, and will stay till we stop using pthreads.
> > 
> > That may happen someday, as one of the main reason for pthread was the
> > (blocking ioctl) libdevmapper event collection. And this is being
> > superseded by path status uevents.
> > 
> > But not soon enough, and the private namespace stuff suffers from lack
> > of friendliness anyway : we can't expect users to grasp easily that
> > changing their prioritizer in /sbin won't be seen by the multipath
> > daemon till restart, for example.
> > 
> > So I propose to start playing with your prioritizers-as-lib idea to see
> > if it's practical.
> > 
> > I prepared the following patch to that effect. It is not complete
> > (actually segfaults, no useful prioritizer ported) but can start fixing
> > bugs and go where ever your personnal interest leads.
> > 
> I'm sorry I forgot to post the git-cached part of the changeset, i.e.
> libprio/ files.
> 
> There it goes.

Upstream git hosts the initial libprio/ commit.

I ported all useful prioritizers, leaving balance_units in the dark.
(If someone is actually using it, please say so)

This time, I cared for a bit of testing and the stuff seems to actually
work.

Now I'm interested in feedback from the Netapp fault injection team.
And any other feedback.

Regards,
cvaroqui
>