iscsi client hangs performing I/O on a dead target

[Danny Braniss]

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> On Wed, Jan 7, 2009 at 10:33 AM, Danny Braniss <danny at cs.huji.ac.il> wrote:
> 
> > > Hi,
> > >
> > > I'm experimenting on iscsi; both the target and the initiator are vmware
> > > virtual machines and are running 7.0-RELEASE.
> > > So far everything works fine except that the client hangs forever (state
> > is
> > > PHYSWR) if it is accessing (dd if=/dev/zero of=/dev/da0) the device while
> > it
> > > "dies" (shutdown of the target machine).
> > >
> > what happens when you bring back the target?
> >
> > > Is this the expected behaviour?
> > >
> > yes.
> > but maybe it can be 'fixed', I'm concidering adding some kind of timeout
> > flag/option.
> >
> > > I would like to be able to configure a timeout so the command that is
> > trying
> > > to access the unavailable device fails and I can handle the problem but I
> > > can't find anything in iscontrol man pages.
> > >

> > > Thanks,
> > > Angelo
> > > _______________________________________________
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> > > http://lists.freebsd.org/mailman/listinfo/freebsd-scsi
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> > >
> >
> > Hi Danny,
> 
> 
> thanks for your reply.
> 
> when the target comes back it is reconnected properly by the initiator.
> 
> The usage of iscsi I had in mind was an initiator connecting to two targets
> and using the two devices as parts of a raid 1 array.
> I was expecting that a failure on one of the disks (network down, target
> machine down) would be eventually detected and the raid turned to degraded
> but still usable.
> What happens now to me is that the whole raid device gets unusable for all
> the time the target is down.
> 
> As I said before I am just experimenting. I don't know how other
> implementations of iscsi initiator work and maybe my idea is just insane :)
> 
I don't know either, the RFC does not mention this case - or maybe I missed it 
:-)
But others have raised the issue, and so it got me thinking, but freebsd likes 
to
panic if a disc goes away, so don't hold your breath for a solution soon.

danny

> Thanks,
> Angelo