.. nex1565202435470
.. _deployment-config-options-all-in-one-duplex-configuration:

=====================================
All-in-one (AIO) Duplex Configuration
=====================================

|prod| AIO Duplex provides a scaled-down |prod| deployment
option that combines controller, storage, and worker functionality on a
redundant pair of hosts.

.. contents::
   :local:
   :depth: 1

.. image:: /shared/figures/deploy_install_guides/starlingx-deployment-options-duplex.png
   :width: 800

See :ref:`Common Components <common-components>` for a description of common
components of this deployment configuration.

This deployment configuration provides a solution for situations in which
protection against overall server hardware faults and only a small amount of
cloud processing / storage power is required.

HA services run on the controller function across the two physical servers in
either Active/Active or Active/Standby mode.

The optional storage function is provided by a small-scale two node Ceph
cluster using one or more disks/|OSDs| from each server, and provides the
backend for Kubernetes' |PVCs|.

The typical solution requires two or more disks per server; one for system
requirements and container ephemeral storage, and one or more for Ceph
|OSDs|.

Optionally, instead of using an internal Ceph cluster across servers, you can
configure an external Netapp Trident storage backend.

Hosted application containers are scheduled on both worker functions.

In the event of an overall server hardware fault:

.. _deployment-config-options-all-in-one-duplex-configuration-ul-jr3-tcy-q3b:

-   all controller HA services enter active mode on the remaining healthy
    server, and

-   all hosted application containers impacted by the failed server are
    recovered on the remaining healthy server.

On an All-in-one Duplex system, two modes of connection are supported for the
management and cluster host network.

**Direct**
    This mode uses direct peer-to-peer connections between the two nodes for
    the management and an internal cluster host network connection,
    eliminating the need for a |ToR| switch port for these
    networks.

    |org| recommends a 10GE shared management and cluster host network with
    |LAG| for direct connections. If the management
    network must be 1GE (to support PXE booting), then a separate 10GE
    cluster host network with |LAG| is also
    recommended. The use of |LAG| addresses failover
    considerations unique to peer-to-peer connections.

**Switch-based**
    This mode uses a |ToR| switch to complete the
    management and cluster host network connections.

.. _deployment-config-options-all-in-one-duplex-configuration-section-N10099-N1001C-N10001:

----------------------
Intel Xeon D Processor
----------------------

In addition to regular all-in-one deployments, |prod| Simplex and Duplex
provide support for small scale deployments on the Intel Xeon D family of
processors using a smaller memory and CPU footprint than the standard Simplex
configuration.

For low-cost or low-power applications with minimal performance demands (40
containers or fewer), |prod| Simplex can be deployed on a server with a
single Intel Xeon D class processor. The platform-reserved memory and the
maximum number of worker threads are reduced by default, but can be
reconfigured if required.

.. _deployment-config-options-all-in-one-duplex-configuration-section-N100AA-N1001C-N10001:

---------------------------------------------------
Extending the capacity of the AIO-Duplex Deployment
---------------------------------------------------

Up to fifty worker/compute nodes can be added to the  All-in-one Duplex
deployment, allowing a capacity growth path if starting with an AIO-Duplex
deployment.

.. image:: /deploy_install_guides/release/figures/starlingx-deployment-options-duplex-extended.png
   :width: 800

The extended capacity is limited up to fifty worker/compute nodes as the
controller/worker function on the AIO controllers has only a portion of the
processing power of the overall server.

Hosted application containers can be scheduled on either of the AIO controller
nodes and/or the worker nodes.