iscsi client hangs performing I/O on a dead target

[Angelo]

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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> >
>
> 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 :)

Thanks,
Angelo