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On Mon, Sep 20, 2021 at 12:18 PM wodel youchi <wodel.youchi at gmail.com> wrote:
>
> Hi,
>
> Thanks, your answer about pacemaker raised another question, VM (instances) high availability is managed by peacemaker in TripleO, could this be a problem when using HCI deployment?

Yes, it's not a recommended combination for the same reasons.

  John

>
>
> Regards.
>
> Le lun. 20 sept. 2021 à 16:59, John Fulton <johfulto at redhat.com> a écrit :
>>
>> On Mon, Sep 20, 2021 at 11:46 AM wodel youchi <wodel.youchi at gmail.com> wrote:
>> >
>> > Hi,
>> >
>> > Is it technically possible to install openstack tripleO on 3 nodes, such that all 3 nodes play the roles of controller compute and ceph storage (hci) at the same time, with replication and HA and all?
>>
>> It's technically possible for a POC (just compose a role [1]
>> accordingly) but it's not a recommended configuration because the
>> controllers use pacemaker with power fencing which you don't want
>> running on your OSD hosts. E.g. pacemaker could take out 1/3rd of your
>> OSDs and make the cluster backfill. If you're short on nodes then one
>> option is to use four. One as a basic KVM hypervisor to host VMs
>> including a virtual undercloud and three virtual controllers. Then use
>> three physical HCI nodes which host the VMs and OSDs.
>>
>>   John
>>
>> [1] https://docs.openstack.org/project-deploy-guide/tripleo-docs/latest/features/custom_roles.html
>>