Date: Fri, 19 Jun 2015 09:20:15 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Max Gurtovoy <maxg@mellanox.com> Cc: freebsd-scsi@freebsd.org, Sagi Grimberg <sagig@mellanox.com>, Oren Duer <oren@mellanox.com>, Hans Petter Selasky <hanss@mellanox.com> Subject: Re: gmultipath HA over iscsi/iser Message-ID: <20150619162015.GD96349@funkthat.com> In-Reply-To: <557DA8C0.1020209@mellanox.com> References: <557DA8C0.1020209@mellanox.com>
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Max Gurtovoy wrote this message on Sun, Jun 14, 2015 at 19:16 +0300: > lately I was testing HA using gmultipath utility over iSCSI/iSER devices. > I'm working on 11-current code base. > I created 1 LUN on the target side and connected via 2 different > physical ports from the initiator side. > On the initiator side I see see /dev/da0 and /dev/da1. > I created multipath device using: > gmultipath label dm0 /dev/da0 /dev/da1. > Now I have new device /dev/multipath/dm0. > I set kern.iscsi.fail_on_disconnection=1 (to fail IO fast). > > Issue 1: > ------------- > I can't run simple fio/dd traffice over /dev/da0 nor /dev/da1. > The only traffic that possible is using the multipath device dm0. > Is this by design ? This is probably because geom only lets one writer open the device at a time, and when the dm0 device is open, it blocks any other writers to it's underlying devices... There is a special geom debug flag that you can set to avoid this... > In the linux implementation we can run traffic on both block devices and > multipath devices. > > Issue 2: > -------------- > I run some fio traffic utility over multipath device dm0 on initiator > side with port toggling in a loop > > Port 1 down --> sleep 2 mins (iSCSI/ISER device reconnecting meanwhile > with no success) --> port 1 up --> sleep 5 mins (iSCSI/ISER device > reconnecting successecfully) > Port 2 down --> sleep 2 mins (iSCSI/ISER device reconnecting meanwhile > with no success) --> port 2 up --> sleep 5 mins (iSCSI/ISER device > reconnecting successecfully) > > The expected result is that when the port N is down than the traffic > moves to the available port and continue succesfully. > I run this test for many hours and traffic FAILED (even though there was > at least 1 suitable path between initiator and target). Someone else will need to answer this one... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."
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