Hi Ivan, Nathanaël and everyone,

Today, I finally upgraded this oVirt 3.5.2 into 3.6.1, and I saw appearing the gluster network in the networks settings.
I'm not using it yet because I still have questions.

I think I perfectly understood your answer, but there are points I'd like to know better :

- I'm not sure that using DNS or /etc/hosts is making any difference. Once every dedicated NIC is using a dedicated ip address, with the dedicated DNS-record + PTR, I see no benefit to use /etc/hosts... ?

- The oVirt setup I'm working on in this discussion is an storage+compute setup (oVirt+gluster on the same hosts). That means that my oVirt nodes are both clients and servers of themselves - data storage speaking.
I'm worrying about not specifying any gateway for the gluster network :
* How will all my hosts - as gluster clients - be able to find a route towards the gluster network (gluster servers)? * How will my guest - my VMs as gluster clients - be able to find a route towards the gluster network (indeed, sometimes also provided that way!) ?

- Obviously, all this wouldn't be that fun if is wasn't already in production (well OK, QA), and thus I have to change the ip of my gluster nodes (https://www.gluster.org/pipermail/gluster-users/2014-May/017328.html).

--
Nicolas ECARNOT

Le 27/11/2015 20:00, Ivan Bulatovic a écrit :
Hi Nicolas,

what works for me in 3.6 is creating a new network for gluster within
oVirt, marking it for gluster use only, optionally setting bonded
interface upon NIC's that are dedicated for gluster traffic and
providing it with an IP address without configuring a gateway, and then
modifying /etc/hosts so that hostnames are resolvable between nodes.
Every node should have two hostnames, one for ovirtmgmt network that is
resolvable via DNS (or via /etc/hosts), and the other for gluster
network that is resolvable purely via /etc/hosts (every node should
contain entries for themselves and for each gluster node).

Peers should be probed via their gluster hostnames, while ensuring that
gluster peer status contains only addresses and hostnames that are
dedicated for gluster on each node. Same goes for adding bricks,
creating a volume etc.

This way, no communication (except gluster one) should be allowed
through gluster dedicated vlan. To be on the safe side, we can also
force gluster to listen only on dedicated interfaces via
transport.socket.bind-address option (haven't tried this one, will do).

Separation of gluster (or in the future any storage network), live
migration network, vm and management network is always a good thing.
Perhaps, we could manage failover of those networks within oVirt, ie. in
case lm network is down - use gluster network for lm and vice versa.
Cool candidate for an RFE, but first we need this supported within
gluster itself. This may prove useful when there is not enough NIC's
available to do a bond beneath every defined network. But we can still
separate traffic and provide failover by selecting multiple networks
without actually doing any load balancing between the two.

As Nathanaël mentioned, marking network for gluster use is only
available in 3.6. I'm also interested if there is a better way around
this procedure, or perharps enhancing it.

Kind regards,

Ivan

On 11/27/2015 05:47 PM, Nathanaël Blanchet wrote:
Hello Nicolas,

Did you have a look to this :
http://www.ovirt.org/Features/Select_Network_For_Gluster ?
But it is only available from >=3.6...

Le 27/11/2015 17:02, Nicolas Ecarnot a écrit :
Hello,

[Here : oVirt 3.5.3, 3 x CentOS 7.0 hosts with replica-3 gluster SD
on the hosts].

On the switchs, I have created a dedicated VLAN to isolate the
glusterFS traffic, but I'm not using it yet.
I was thinking of creating a dedicated IP for each node's gluster
NIC, and a DNS record by the way ("my_nodes_name_GL"), but I fear
using this hostname or this ip in oVirt GUI host network interface
tab, leading oVirt think this is a different host.

Not being sure this fear is clearly described, let's say :
- On each node, I create a second ip+(dns record in the soa) used by
gluster, plugged on the correct VLAN
- in oVirt gui, in the host network setting tab, the interface will
be seen, with its ip, but reverse-dns-related to a different hostname.
Here, I fear oVirt might check this reverse DNS and declare this NIC
belongs to another host.

I would also prefer not use a reverse pointing to the name of the
host management ip, as this is evil and I'm a good guy.

On your side, how do you cope with a dedicated storage network in
case of storage+compute mixed hosts?





--
Nicolas ECARNOT
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