Comment 6 for bug 1135453

On Friday 01 March 2013 05:49 PM, Mike Burgener wrote:
> defaults {
> udev_dir /dev
> polling_interval 30
> selector "round-robin 0"
> path_grouping_policy multibus
> getuid_callout "/lib/udev/scsi_id --whitelisted --device=/dev/%n"
> prio_callout /bin/true
> path_checker readsector0
> prio const
> rr_min_io 100
> rr_weight uniform
> failback immediate
> no_path_retry 12
> user_friendly_name yes
> hardware_handler "0"
> }

The behavior you reported is pretty interesting. You reported that you
suffered the hang state because the umount occurred after the multipathd
and iscsid processes were killed by the init scripts (which I also
assumed given the new init systems, upstart and systemd).

But looking at your config, you should not typically see the hang
scenario. I was suspecting that you might be using the multipath
queue_if_no_path feature, but that is not the case here. The iscsi
replacement timeouts are also the defaults, i.e. 120 seconds, which
would mean that after 120 seconds of retry, iscsi will error out and the
errors will propagate to the upper layers.

Ideally, with the configuration settings that you have, you should see
the errors show up after 120 seconds, and NOT hang. I have no more ideas
on what might be going wrong in your setup. Perhaps the Ubuntu multipath
maintainer might have some insight to this.

--
Ritesh Raj Sarraf
RESEARCHUT - http://www.researchut.com
"Necessity is the mother of invention."