[rhelv6-list] Seeing only ONE session/device instead of TWO

[Prashanth Sundaram]

Thanks for the response Phil.

/etc/sysctl.conf is correct per your description. 

I see four files in there. What surprises me is that the ifacename,
which is a combination of HWaddr and Mfr does not seem to match the mac
address reported by the system. See below, the last value is an
increment or something.

# ls /var/lib/iscsi/ifaces/
bnx2i.18:03:73:f2:fc:b3  bnx2i.18:03:73:f2:fc:b5
bnx2i.18:03:73:f2:fc:b7  bnx2i.18:03:73:f2:fc:b9

# ifconfig | grep 'HWaddr'
em1       Link encap:Ethernet  HWaddr 18:03:73:F2:FC:B2
em2       Link encap:Ethernet  HWaddr 18:03:73:F2:FC:B4
em3       Link encap:Ethernet  HWaddr 18:03:73:F2:FC:B6
em4       Link encap:Ethernet  HWaddr 18:03:73:F2:FC:B8


Also in the actual file. I tried deleting, but it picks up the same name
and values. For example, see the entry 

# BEGIN RECORD 2.0-872.33.el6
iface.iscsi_ifacename = bnx2i.18:03:73:f2:fc:b7
iface.hwaddress = 18:03:73:f2:fc:b7
iface.transport_name = bnx2i
iface.vlan_id = 0
iface.vlan_priority = 0
iface.iface_num = 0
iface.mtu = 0
iface.port = 0
# END RECORD


I am referring to this guide. 
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Storag
e_Administration_Guide/iscsioffloadmain.html

My NIC is capable of Offloading ISCSI, but not sure if I should enable
it. So If I stick to Software_ISCSI, I should see 2 connections. 

The interface used by iscsi is called "default"

# iscsiadm -m discovery -t st -p 10.10.100.200:3260 -P 1
Target:
iqn.2001-05.com.equallogic:8-cb2b76-511758f4a-f4016309f414f7a1-fs-proj-0
1
        Portal: 10.10.100.200:3260,1
                Iface Name: default



Still not sure where the problem lies.




-----Original Message-----
From: rhelv6-list-bounces at redhat.com
[mailto:rhelv6-list-bounces at redhat.com] On Behalf Of Phil Meyer
Sent: Tuesday, April 03, 2012 5:44 PM
To: rhelv6-list at redhat.com
Subject: Re: [rhelv6-list] Seeing only ONE session/device instead of TWO

On 04/03/2012 02:16 PM, Prashanth Sundaram wrote:
>
> Hello,
>
> I am having some trouble with ISCSI to work on  RHEL 6.2. It currently

> is using 1 nic to connect to SAN and shows only 1 session instead of 
> 2. I have configured TWO nics(em3 & em4) to perform multipathing and 
> have verified that both can connect to SAN.
>
> Any ideas how to get multipath to work? I only see 1 device instead of

> 2 in multipath. Please see my config below.
>
> Another strange thing is that the iface_name has different MAC address

> than what ifconfig shows.
>
>


Two main issues.

On the same network, two interfaces need to negotiate ARP independently 
of each other.  If not, a packet can exit one interface, and be sent a 
response to another interface.  That does not work.

/etc/sysctl.conf needs to be adjusted for ARP by interface.
Clues:
# net
# net.ipv4.conf.all.arp_filter = 1
# net.ipv4.conf.all.rp_filter = 1
# net.ipv4.conf.default.arp_filter = 1
net.ipv4.conf.all.arp_ignore=1
net.ipv4.conf.all.arp_announce=2

ISCSI needs to be told that there are two interfaces, it does not know 
it by default.

This is done by special files in: /var/lib/iscsi/ifaces

I don't have a sample nearby, but that should get you googleing ok.

Once that is in place, 'iscsiadm -m node -l' will show two logins for 
every target.
If THAT happens, 'multipath -r' will show two connections per device.

Good Luck!

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