Dell Linux Wiki - open-iscsi, iface, and mpio

[JACOB_LIBERMAN at Dell.com]

Hi Joe,

The person who wrote that is a Red Hat employee who worked in our lab.  He has since moved on.  If you reply to me directly with your questions, I can try to help you.

Thanks, Jacob

> -----Original Message-----
> From: linux-poweredge-bounces at lists.us.dell.com [mailto:linux-
> poweredge-bounces at lists.us.dell.com] On Behalf Of Hoot, Joseph
> Sent: Tuesday, July 07, 2009 7:07 AM
> To: Iyer, Shyam; linux-poweredge-Lists
> Subject: RE: Dell Linux Wiki - open-iscsi, iface, and mpio
> 
> Here is a copy and paste from an email I sent to others currently
> working on our issue.  I'm trying to clarify how iscsiadm works with
> the
> ifaces:
> 
> =================START PASTE
> Don,
> 
> On July 22, 2008 you had written to the open-iscsi mailing list.  Here
> is a link to that post:
> 
> http://groups.google.com/group/open-iscsi/msg/f94fbc5f66202e61?
> 
> In that post, you mentioned using the following:
> 
> Portal: 172.23.10.242
> iface.eth0: 172.23.49.170
> iface.eth1: 172.23.49.171
> 
> What I'm trying to find out is a definite answer on how the `iscsiadm -
> m
> iface` works --specifically with respect to linux routing.  ITEC would
> like to use the iface to allow for multiple sessions to connect to the
> same volume.  However, what we're having trouble with is understanding
> what happens from an iSCSI perspective when we use the ifaces.  In
> addition, we'd like to help Oracle understand this as well (if they in
> fact have any doubts).
> 
> Do you happen to have any connections with any of the open-iscsi
> developers?  If so, would you be able to pose a question to them on our
> behalf?
> 
> 1) iface networks - with regards to `iscsiadm -m iface` with software
> iSCSI initiators, was the design meant to work with two interfaces on
> the same network segment or with the interfaces being on different
> segments?  In the scenario where they are on the same network segment,
> standard linux routing would send any outbound traffic out whichever
> interface appears first in the list of routes.  In our situation eth2
> and eth3 being dedicated to ifaces eth2 and eth3 respectively.  When
> sessions are created out both ifaces and logged in, whenever I/O goes
> to
> eth2 (if standard linux routing is involved) all traffic would go out
> eth2 (since it happens to be the first that appears in my `netstat -rn`
> list).  However, when iface eth3 is used for I/O, (again, if standard
> linux routing is involved) wouldn't all outbound I/O attempt to be
> routed down eth2?
> 
> I know that, during an earlier email I sent, you already said that the
> initiator would take care of it but ITEC and Oracle are both trying to
> understand how.
> 
> By the way, I'm still working on getting a 5.3 system running for
> testing purposes.
> =================END PASTE
> 
> 
> Thanks,
> Joe
> 
> 
> 
> -----Original Message-----
> From: Shyam_Iyer at Dell.com [mailto:Shyam_Iyer at Dell.com]
> Sent: Tuesday, July 07, 2009 5:05 AM
> To: Hoot, Joseph; linux-poweredge at lists.us.dell.com
> Subject: RE: Dell Linux Wiki - open-iscsi, iface, and mpio
> 
> > -----Original Message-----
> > From: linux-poweredge-bounces at lists.us.dell.com [mailto:linux-
> > poweredge-bounces at lists.us.dell.com] On Behalf Of Hoot, Joseph
> > Sent: Tuesday, July 07, 2009 5:42 AM
> > To: linux-poweredge-Lists
> > Subject: Dell Linux Wiki - open-iscsi, iface, and mpio
> >
> > I'm trying to find out who wrote the following wiki article:
> >
> >
> http://linux.dell.com/wiki/index.php/Products/HA/DellRedHatHALinuxClust
> > e
> > r/Storage/EqualLogic_PS-
> > Series/Cluster_Nodes#Configure_iSCSI_Initiators_
> > for_Multipath
> >
> > I have been working with Dell and Oracle representatives with regards
> > to
> > getting multiple sessions to an iSCSI EqualLogic volume working
> behind
> > dm-multipath.  We're trying to understand how the open-iscsi
> > implementation works under the hood.  This article seems to sum up
> what
> > we've done, but I'd like to see if any open-iscsi developers were
> > involved.
> >
> > Thanks,
> > Joe
> 
> Joe - I am not too sure on the author but we have a few iSCSI guys on
> this list. Specific questions would help.
> 
> For starts each EQL volume is associated with an iqn and hence you can
> build multiple sessions by creating multiple initiator portals at the
> host side.
> 
> Each of them would login to the EQL volume portal through iface
> bindings
> -
> 
> Ifaces(upstream code) could be created based on the following -
> a) IQN
> b) MAC address
> c) interface name
> d) transport type
> 
> -Shyam Iyer
> 
> 
> 
> 
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