[Users] CentOS 6 and multiple ISCSI interfaces/multipath

[Gary Lloyd]

Dan Yasny <dyasny at ...> writes:
> 
> 
> This is an old issue with EQL, best practice is to have different iSCSI 
paths on different subnets or VLANs, and to login to every iSCSI portal when 
you create the storage domain. 
> Alternatively, you can use bonds of course
> 
> 
> On Thu, Jun 13, 2013 at 4:41 PM, Martin Goldstone <m.j.goldstone-
gMJiioYAC8g at public.gmane.org.uk> wrote:
> Hi all,
> I've recently started looking at oVirt to provide the next iteration of 
our virtualization infrastructure, as we have recently acquired some ISCSI 
storage. Up to now, we've been using KVM managed by libvirt/virt-manager 
locally on each of our hosts, using direct attached storage, which was 
obviously less than ideal.
> 
> 
> In setting it all up, I've hit a bit of a snag. We've got 4 GbE network 
interfaces on our pilot host (running vdsm on CentOS 6.4) which are 
connected to our storage arrays (equallogic). I've created 4 interfaces with 
iscsiadm for these and bound them, but when setting up the discs in oVirt, 
I've not seen a way of telling it which interfaces to use. The node makes 
the connection to the target successfully, but it seems its only connecting 
via the "default" iscsi interface, and not making a connection via each 
interface that I've defined. Obviously this means I can't use multipath, and 
being only GbE interfaces it means I'm not getting the performance I should.
> 
> 
> I've done some searching via Google, but I've not really found any thing 
that helps. Perhaps I've missed something, but can anyone give me any 
pointers for getting this to work across multiple interfaces?
> 
> 
> Thanks?
> 
> Martin
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Hi Dan

I work with Martin.

The problem we are having seems to be with regards to how ovirt/vdsm manages 
iscsi sessions and not how our server is connected. I have manually tested 
iscsiadm on the same machine(Centos 6.4) and we are indeed getting multiple 
sessions from 2 ifaces with mpio working via dm-multipath, etc. 

vdsm however does not appear to be logging into the targets using the ifaces 
we use in iscsiadm, I have tried adding this to /etc/vdsm/vdsm.conf, but it 
makes little difference:

[irs]
iscsi_default_ifaces = eth2,eth3

Thanks

Gary