[ovirt-users] ISCSI storage with multiple nics on same subnet disabled on host activation

[Nelson Lameiras]

Hello, 

In our oVirt hosts, we are using DELL equallogic SAN with each server connecting to SAN via 2 physical interfaces. Since both interfaces share the same network (Equalogic limitation) we must patch the linux kernel to to allow iSCSI multipath with multiple NICs in the same subnet with sysctl : 

-------------------------------------------------------------------------------------------- 
net.ipv4.conf.p2p1.arp_ignore=1
net.ipv4.conf.p2p1.arp_announce=2
net.ipv4.conf.p2p1.rp_filter=2

net.ipv4.conf.p2p2.arp_ignore=1
net.ipv4.conf.p2p2.arp_announce=2
net.ipv4.conf.p2p2.rp_filter=2 



-------------------------------------------------------------------------------------------- 



This works great in most setups, but for a strange reason, on some of our setups, the sysctl configuration is updated by VDSM when activating a host and the second interface stops working immeadiatly : 
-------------------------------------------------------------------------------------------- 
vdsm.log 
2017-06-07 11:51:51,063+0200 INFO  (jsonrpc/5) [storage.ISCSI] Setting strict mode rp_filter for device 'p2p2'. (iscsi:602)
2017-06-07 11:51:51,064+0200 ERROR (jsonrpc/5) [storage.HSM] Could not connect to storageServer (hsm:2392)
Traceback (most recent call last):
  File "/usr/share/vdsm/storage/hsm.py", line 2389, in connectStorageServer
    conObj.connect()
  File "/usr/share/vdsm/storage/storageServer.py", line 433, in connect
    iscsi.addIscsiNode(self._iface, self._target, self._cred)
  File "/usr/lib/python2.7/site-packages/vdsm/storage/iscsi.py", line 232, in addIscsiNode
    iscsiadm.node_login(iface.name, target.address, target.iqn)
  File "/usr/lib/python2.7/site-packages/vdsm/storage/iscsiadm.py", line 337, in node_login
    raise IscsiNodeError(rc, out, err) 




-------------------------------------------------------------------------------------------- 

"strict mode" is enforced for second interface, and it no longuer works... 
Which means - at least - that there is no redundancy in case of hardware faillure and this is not acceptable for our production needs. 

What is really strange is that we have another "twin" site on another geographic region with simillar hardware configuration and same oVirt installation, and this problem does not happen. 

What can be the root cause of this behaviour? How can I correct it? 

our setup: 
hostedEngine : Centor 7.3, ovirt 4.1.2 
3 physical nodes centos 7.3, ovirt 4.1.2 
SAN DELL Equalogic 

cordialement, regards, 


	Nelson LAMEIRAS 
Ingénieur Systèmes et Réseaux / Systems and Networks engineer 
Tel: +33 5 32 09 09 70 
nelson.lameiras at lyra-network.com 

www.lyra-network.com | www.payzen.eu 

	
	
	

Lyra Network, 109 rue de l'innovation, 31670 Labège, FRANCE 

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