[ovirt-users] 4-node oVirt with replica-3 gluster

[Goorkate, B.J.]

Hi Sahina,

First: sorry for my delayed response. I wasn't able to respond earlier.

I already planned on adding the 4th node as a gluster client, so thank you for
confirming that this works.

Why I was in doubt is that certain VMs with a lot of storage I/O on the 4th node have to
replicate to 3 other hosts (the replica-3 gluster nodes) over the storage network, while
a VM on 1 of the replica-3 gluster nodes only has to replicate to two other nodes over
the network, thus creating less network traffic. 

Does this make sense?

And if it does: can that be an issue? 

Regards,

Bertjan

On Fri, Sep 23, 2016 at 04:47:25PM +0530, Sahina Bose wrote:
> 
> 
> On Fri, Sep 23, 2016 at 4:14 PM, Davide Ferrari <davide at billymob.com> wrote:
> 
>     I'm struggling with the same problem (I say struggling because I'm still
>     having stability issues for what i consider a stable cluster) but you can:
>     - create a replica 3 engine gluster volume
>     - create replica 2 data, iso and export volumes
> 
> 
> What are the stability issues you're facing? Data volume if used as a data
> storage domain should be a replica 3 volume as well.
>  
> 
> 
>     Deploy the hosted-engine on the first VM (with the engine volume) froom the
>     CLI, then log in Ovirt admin, enable gluster support, install *and deploy*
>     from the GUI host2 and host3 (where the engine bricks are) and then install
>     host4 without deploying. This should get you the 4 hosts online, but the
>     engine will run only on the first 3
> 
> 
> Right. You can add the 4th node to the cluster, but not have any bricks on this
> volume in which case VMs will be run on this node but will access data from the
> other 3 nodes.
>  
> 
> 
>     2016-09-23 11:14 GMT+02:00 Goorkate, B.J. <b.j.goorkate at umcutrecht.nl>:
> 
>         Dear all,
> 
>         I've tried to find a way to add a 4th oVirt-node to my existing
>         3-node setup with replica-3 gluster storage, but found no usable
>         solution yet.
> 
>         From what I read, it's not wise to create a replica-4 gluster
>         storage, because of bandwith overhead.
> 
>         Is there a safe way to do this and still have 4 equal oVirt nodes?
> 
>         Thanks in advance!
> 
>         Regards,
> 
>         Bertjan
> 
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>     --
>     Davide Ferrari
>     Senior Systems Engineer
>    
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