How to: Manage Load Balancing
=============================

From the Load Balancing page in NodeWorx, administrators can manage the Load Balancer status, and add new Load
Balanced Services

.. contents::

To Manage the Load Balancer
---------------------------

Checking the Load Balancer Status
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

#. Log into NodeWorx from the browser on the Cluster Manager (https://ip.ad.dr.ess:2443/nodeworx)
#. In NodeWorx, navigate to **Clustering > Load Balancing**
#. Under Load Balancer Control, the Status bar indicates the current status of the service

   - It is also possible to control the status of the service from this interface:

      - **Play** starts the service
      - **Arrow** restarts/refreshes the service
      - **Stop** stops the service

.. image:: /images/cluster-lb-status.png
   :alt: load balancer status 

Setting Load Balancer Start-On-Boot Options 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

#. Log into NodeWorx from the browser on the Cluster Manager (https://ip.ad.dr.ess:2443/nodeworx)
#. In NodeWorx, navigate to **Clustering > Load Balancing**
#. Under Load Balancer Control, select either **Yes** or **No** from the Start on Boot-up dropdown 
#. Click **Update**


To Add a New Load Balanced Service
----------------------------------

#. Log into NodeWorx from the browser on the Cluster Manager (https://ip.ad.dr.ess:2443/nodeworx)
#. In NodeWorx, navigate to **Clustering > Load Balancing**
#. Under Load Balanced Service, click **+**. This opens the Add New Service form
#. Update the required fields: 

   - **Service/Port**: The service to load balance. Options include http, https, and both secure and insecure mail 
     services
   - **Virtual IP**: The virtual IP will be shared and load-balanced
   - **Policy**:

     - **Round Robin**: Default load balancer policy. Incoming traffic is rotated sequentially to each 
       server. After each server has received a connection, the load balancer repeats the list in the same order
     - **Weighted Round Robin**: Builds on simple Round-robin load balancing to account for differing 
       application server characteristics. The administrator assigns a weight to each server, which determines the order
       of the rotation
     - **Least Connection**: Dynamic load balancing, where client requests are distributed to the server with 
       the least number of active connections at the time the request is received 
     - **Weighted Least Connection**: Builds on Least Connection load balancing to account for differing application 
       server characteristics. The administrator assigns a weight to each server based on the server's traffic-handling 
       capability 
     - **Locality-Based Least Connection**: Each IP, or group of IP addresses is attached, not to individual servers, 
       but to the entire server group. Requests are sent to the server under the lightest load. If all of the servers 
       in the native group are overloaded, then another under-loaded server from the cluster is picked up and added 
       to the group servicing the IP the request came from. The server with the lightest load will then be deleted 
       from the group
   
   - **Persistant**: The length of time a client will remain connected to the same server in a session 
   
   .. image:: /images/cluster-add-lb-service.png
      :alt: add lb service form

#. Click **Continue**. This opens the Confirmation form
#. Click **Save**

To Edit a Load Balanced Service
-------------------------------

#. Log into NodeWorx from the browser on the Cluster Manager (https://ip.ad.dr.ess:2443/nodeworx)
#. In NodeWorx, navigate to **Clustering > Load Balancing**
#. Under Load Balanced Services, click the **Pencil** next to the service to edit. This opens the Load Balanced Services
   form

   .. image:: /images/cluster-lb-edit.png
      :alt: load balancer edit form 

#. Update the desired fields
#. Click **Save**

To Delete a Load Balanced Service
---------------------------------

#. Log into NodeWorx from the browser on the Cluster Manager (https://ip.ad.dr.ess:2443/nodeworx)
#. In NodeWorx, navigate to **Clustering > Load Balancing**
#. Under Load Balanced Services, click the **Trashcan** next to the service to edit. This opens the Confirmation form 

   .. image:: /images/cluster-delete-lb-service.png
      :alt: load balancer edit form 

#. Click **Delete**