Modifying the Load Balancing Route Properties

Once you have created a load balancing deployment, you can modify the properties of the route. The properties to modify will depend on the type of load balancing algorithm attached to the route.

To modify a load balancing route properties, use the dsconfig set-load-balancing-route-prop command.

You can modify the following properties on a load balancing route, depending on the load balancing algorithm:

Setting the Priority in Failover Algorithm

Once you have created a load balancing deployment using the failover algorithm, you can modify the proxy workflow element to change the route used, as well as the priority of the route. In a failover algorithm, the route with a priority of 1 is the main route used, while the route with 2 (or more) are the secondary routes, used in case of failure on the primary route.

For example, if the route load-bal-route1 was initially set as the main route with a priority set to 1, but you now want to make it the backup route, you can set the priority to 2 using the following command line.

$ dsconfig -h localhost -p 4444 -D "cn=Directory Manager" -w password -X -n \
  set-load-balancing-route-prop \
  --element-name load-bal-we1 \
  --route-name load-bal-route1
  --set priority: 2

Note - You can have two routes with the same priority, but in this case, the choice of the active route which treats the request is not deterministic.

In the example above, if you want the load-bal-route1 to be the secondary route, then you must make sure that your other load balancing route is modified to a priority of 1.

Setting the switch-back Flag

After failover, the route with the backup route continues to handle all incoming requests, even once the priority server which had failed becomes available again. Switch-back to the primary route does not automatically occur unless the switch-back flag has been set to true. By default, the switch-back flag is set to false.

The switch-back flag is an advanced property. To set the switch-back flag to true, do the following:

$ dsconfig -h localhost -p 4444 -D "cn=Directory Manager" -w password -X -n \
  --advanced set-load-balancing-route-prop \
  --element-name load-bal-we1 \
  --route-name load-bal-route1
  --set switch-back: true

Setting the Weight of a Proportional Algorithm

Once you have created a load balancing deployment using the proportional algorithm, you can modify the proxy workflow element to change the route used, as well as the weight of a route. The weight can be different for each operation type. The value of the weight should be 0 or more, were 0 indicates that the route will not be used for the specified operation.

Using the interactive mode of dsconfig, you can see that the following properties can be modified:

>>>> Configure the properties of the Proportional Load Balancing Route

        Property          Value(s)
        ---------------------------
    1)  add-weight        1
    2)  bind-weight       1
    3)  compare-weight    1
    4)  delete-weight     1
    5)  extended-weight   1
    6)  modify-weight     1
    7)  modifydn-weight   1
    8)  search-weight     1
    9)  workflow-element  proxy-we1

For example, if you initially set all your routes to a weight of 1 on all operations, then all the servers will handle an equal ratio of operations. However, if you want a remote LDAP server to handle more search requests than the other servers in the deployment, then you can set its search-weight to a higher value, such as 5. To do so, use the following command:

$ dsconfig -h localhost -p 4444 -D "cn=Directory Manager" -w password -X -n \
  set-load-balancing-route-prop \
  --element-name load-bal-we1 \
  --route-name load-bal-route1 \
  --set search-weight:5

Note - If you want to modify the weight for all the operations, you will have to modify the weight for each operation.

If you want to modify load-bal-route1 to handle twice the operations as your other route, then you would need to set the weight of all operations to 2 (assuming the weight on the other route is set to 1). In other words, run the command as follows:

$ dsconfig -h localhost -p 4444 -D "cn=Directory Manager" -w password -X -n \
  set-load-balancing-route-prop \
  --element-name load-bal-we1 \
  --route-name load-bal-route1 \
  --set add-weight:2 \
  --set bind-weight:2 \
  --set compare-weight:2 \
  --set delete-weight:2 \
  --set extended-weight:2 \
  --set modify-weight:2 \
  --set modifydn-weight:2 \
  --set search-weight:2 

If you set the weight to 0 for any of the operations, then the route will not perform the specified operation. For example, if you set add-weight to 0, as follows, then load-bal-route1 will not forward any add requests to the associated remote LDAP server. Moreover, if all the routes indicate a weight of 0 for a specific operation, then that operation will not be supported.

Setting the Threshold in Saturation Algorithm

Once you have created a load balancing deployment using the saturation algorithm, you can modify the proxy workflow element used, the priority of the route, the saturation threshold, and the saturation threshold alert.

With a saturation algorithm, requests are distributed based on two criteria: the priority of the server and the saturation threshold of the server. The saturation threshold is the limit at which the server is considered “maximized” and service may become degraded. In a load balancing deployment with saturation algorithm, requests are sent to the server with the highest priority (1) until the server reaches the saturation threshold indicated.

For example, if you indicate load-bal-route1 as the server with the highest priority, with a threshold of 80%, all requests will be sent to load-bal-route1 until its saturation threshold goes over 80%. Once it exceeds 80%, then requests are routed to the next server in the priority list.

>>>> Configure the properties of the Saturation Load Balancing Route

        Property          Value(s)
        ---------------------------
    1)  alert-threshold   85
    2)  priority          1
    3)  threshold         80
    4)  workflow-element  proxy-we1

To modify the saturation threshold, use the following command:

$ dsconfig -h localhost -p 4444 -D "cn=Directory Manager" -w password -X -n \
  set-load-balancing-route-prop \
  --element-name load-bal-we1 \
  --route-name load-bal-route1 \
  --set threshold:90

In this example, the saturation threshold has been set to 90%.

Setting the Saturation Threshold Alert

The saturation threshold alert is used to set at which point a notification will be sent to the system administrator to indicate that the server has passed the saturation limit. Generally, the saturation threshold alert is set higher than the saturation limit, in order to indicate if the saturation continues to increase past the saturation threshold (which may indicate a problem). The alert should bet set with an acceptable buffer, as there may be a short delay in which saturation continues to increase slightly before requests are forwarded to another route.

To modify the saturation threshold, use the following command:

$ dsconfig -h localhost -p 4444 -D "cn=Directory Manager" -w password -X -n \
  set-load-balancing-route-prop \
  --element-name load-bal-we1 \
  --route-name load-bal-route1 \
  --set alert-threshold:85

You can set the saturation threshold alert to a value lower than the saturation threshold, in order to perform preventative actions. This may imply receiving notifications even in cases where the saturation threshold is not reached. That is, a saturation threshold alert is sent, but the saturation limit drops and does not reach the saturation threshold. However, the requests will only be sent to the next priority route when the saturation threshold is reached.

For more information on setting the notification message, see Setting LDAP Data Source Monitoring Properties in the Proxy.