[ovirt-users] Multipath handling in oVirt

[Nicolas Ecarnot]

Hello,

Before replying further, may I ask you, Yura, to post a screenshot of 
your iSCSI multipathing setup in the web GUI?

And also the same for the network setup of a host ?

Thank you.

-- 
Nicolas ECARNOT

Le 01/02/2017 à 13:14, Yura Poltoratskiy a écrit :
> Hi,
>
> As for me personally I have such a config: compute nodes with 4x1G nics
> and storages with 2x1G nics and 2 switches (not stackable). All servers
> runs on CentOS 7.X (7.3 at this monent).
>
> On compute nodes I have bonding with two nic1 and nic2 (attached to
> different switches) for mgmt and VM's network, and the other two nics
> nic3 and nic4 without bonding (and also attached to different switches).
> On storage nodes I have no bonding and nics nic1 and nic2 connected to
> different switches.
>
> I have two networks for iSCSI: 10.0.2.0/24 and 10.0.3.0/24, nic1 of
> storage and nic3 of computes connected to one network; nic2 of storage
> and nic4 of computes - to another one.
>
> On webUI I've created network iSCSI1 and iSCSI2 for nic3 and nic4, also
> created multipath. To have active/active links with double bw throughput
> I've added 'path_grouping_policy "multibus"' in defaults section of
> /etc/multipath.conf.
>
> After all of that, I have 200+MB/sec throughput to the storage (like
> raid0 with 2 sata hdd) and I can lose one nic/link/swith without
> stopping vms.
>
> [root at compute02 ~]# multipath -ll
> 360014052f28c9a600000000000000000 dm-6 LIO-ORG ,ClusterLunHDD
> size=902G features='0' hwhandler='0' wp=rw
> `-+- policy='service-time 0' prio=1 status=active
>   |- 6:0:0:0 sdc 8:32  active ready running
>   `- 8:0:0:0 sdf 8:80  active ready running
> 36001405551a9610d09b4ff9aa836b906 dm-40 LIO-ORG ,SSD_DOMAIN
> size=915G features='0' hwhandler='0' wp=rw
> `-+- policy='service-time 0' prio=1 status=active
>   |- 7:0:0:0 sde 8:64  active ready running
>   `- 9:0:0:0 sdh 8:112 active ready running
> 360014055eb8d30a91044649bda9ee620 dm-5 LIO-ORG ,ClusterLunSSD
> size=135G features='0' hwhandler='0' wp=rw
> `-+- policy='service-time 0' prio=1 status=active
>   |- 6:0:0:1 sdd 8:48  active ready running
>   `- 8:0:0:1 sdg 8:96  active ready running
>
> [root at compute02 ~]# iscsiadm -m session
> tcp: [1] 10.0.3.200:3260,1 iqn.2015-09.lab.lnx-san:storage (non-flash)
> tcp: [2] 10.0.3.203:3260,1 iqn.2016-10.local.ntu:storage3 (non-flash)
> tcp: [3] 10.0.3.200:3260,1 iqn.2015-09.lab.lnx-san:storage (non-flash)
> tcp: [4] 10.0.3.203:3260,1 iqn.2016-10.local.ntu:storage3 (non-flash)
>
> [root at compute02 ~]# ip route show | head -4
> default via 10.0.1.1 dev ovirtmgmt
> 10.0.1.0/24 dev ovirtmgmt  proto kernel  scope link  src 10.0.1.102
> 10.0.2.0/24 dev enp5s0.2  proto kernel  scope link  src 10.0.2.102
> 10.0.3.0/24 dev enp2s0.3  proto kernel  scope link  src 10.0.3.102
>
> [root at compute02 ~]# brctl show ovirtmgmt
> bridge name     bridge id               STP enabled     interfaces
> ovirtmgmt               8000.000475b4f262       no bond0.1001
>
> [root at compute02 ~]# cat /proc/net/bonding/bond0 | grep "Bonding\|Slave
> Interface"
> Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
> Bonding Mode: fault-tolerance (active-backup)
> Slave Interface: enp4s6
> Slave Interface: enp6s0
>
>
> 01.02.2017 12:50, Nicolas Ecarnot пишет:
>> Hello,
>>
>> I'm starting over on this subject because I wanted to clarify what was
>> the oVirt way to manage multipathing.
>>
>> (Here I will talk only about the data/iSCSI/SAN/LUN/you name it
>> networks.)
>> According to what I see in the host network setup, one can assign
>> *ONE* data network to an interface or to a group of interfaces.
>>
>> That implies that if my host has two data-dedicated interfaces, I can
>> - either group them using bonding (and oVirt is handy for that in the
>> host network setup), then assign the data virtual network to this bond
>> - either assign each nic a different ip in each a different VLAN, then
>> use two different data networks, and assign them each a different data
>> network. I never played this game and don't know where it's going to.
>>
>> At first, may the oVirt storage experts comment on the above to check
>> it's ok.
>>
>> Then, as many users here, our hardware is this :
>> - Hosts : Dell poweredge, mostly blades (M610,620,630), or rack servers
>> - SANs : Equallogic PS4xxx and PS6xxx
>>
>> Equallogic's recommendation is that bonding is evil in iSCSI access.
>> To them, multipath is the only true way.
>> After reading tons of docs and using Dell support, everything is
>> telling me to use at least two different NICs with different ip, not
>> bonded - using the same network is bad but ok.
>>
>> How can oVirt handle that ?
>>
>


-- 
Nicolas ECARNOT