From owner-freebsd-scsi@FreeBSD.ORG Wed Jun 24 00:14:14 2015 Return-Path: Delivered-To: freebsd-scsi@nevdull.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 8AA0DD19 for ; Wed, 24 Jun 2015 00:14:14 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "gold.funkthat.com", Issuer "gold.funkthat.com" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 6C1FC1F0A; Wed, 24 Jun 2015 00:14:13 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (localhost [127.0.0.1]) by gold.funkthat.com (8.14.5/8.14.5) with ESMTP id t5O0EDes059273 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 23 Jun 2015 17:14:13 -0700 (PDT) (envelope-from jmg@gold.funkthat.com) Received: (from jmg@localhost) by gold.funkthat.com (8.14.5/8.14.5/Submit) id t5O0EDoi059272; Tue, 23 Jun 2015 17:14:13 -0700 (PDT) (envelope-from jmg) Date: Tue, 23 Jun 2015 17:14:13 -0700 From: John-Mark Gurney To: Max Gurtovoy Cc: freebsd-scsi@freebsd.org, Sagi Grimberg , Oren Duer , Hans Petter Selasky , mav@freebsd.org Subject: Re: gmultipath HA over iscsi/iser Message-ID: <20150624001412.GS96349@funkthat.com> References: <557DA8C0.1020209@mellanox.com> <20150619162015.GD96349@funkthat.com> <55897E4B.8060608@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55897E4B.8060608@mellanox.com> X-Operating-System: FreeBSD 9.1-PRERELEASE amd64 X-PGP-Fingerprint: 54BA 873B 6515 3F10 9E88 9322 9CB1 8F74 6D3F A396 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? User-Agent: Mutt/1.5.21 (2010-09-15) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (gold.funkthat.com [127.0.0.1]); Tue, 23 Jun 2015 17:14:13 -0700 (PDT) X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Jun 2015 00:14:14 -0000 Max Gurtovoy wrote this message on Tue, Jun 23, 2015 at 18:42 +0300: > On 6/19/2015 7:20 PM, John-Mark Gurney wrote: > > 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... > > I tried this debug exclusive flag with iSCSI/iSER but when I set it to 0 > the system crushed at the 'gmultipath label ...' stage. > John, > did you try it over iSCSI ? Nope, I didn't.. In fact, I was thinking of another debug flag the one in kern.geom.debugflags, but that one should have worked too... Since it doesn't, please file a bug report and notify the maintainer of multipath with a complete report... > >> 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... > > I'm pretty new in the FreeBSD community so I don't know who is the > maintainer of the gmultipath driver. Though I realize it's difficult, it's easiest to look at the source to see who's been touching it last: https://svnweb.freebsd.org/base/head/sys/geom/multipath/g_multipath.c?view=log Looks like mav has been somewhat active recently... I've cc'd him... > Maybe we can discuss about testing the gmultipath driver over iscsi/iser > devices and fix some bugs together ? I can help out some, but engaging mav, or some of the others that are more active in storage would be better... > We are planning to add it to our test plan and HA is in high priority > for us. You should definately talk/coordinate w/ the people at iXsystems (mav works there), as they work in storage w/ iSCSI, etc. -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."