By default, ZENworks uses ordered closest server lists. This means that even if you have 5 servers in your zone, all the agents will use the first one, unless otherwise configured. ZENworks provides two methods for enabling load balancing of your servers:
The first load balancing method is to define a Server Group within the closest server rule and then add the servers that you want to load balance to the group. This will cause the managed device to randomize the servers in the group during closest server rule evaluation. If none of the servers in the group are available and there are other servers in the list, then those servers will be tried only after all the servers in the group. This means that if there are 6 servers that are all co-located (that is, the network latency to each of these servers from the agents are similar), it is better to create a single group to hold all 6 servers rather than spreading them into multiple groups.
Server Groups are the preferred means of implementing load balancing in ZENworks. The advantages of using a Server Group over an L4 switch include the following:
No costs involved.
Load balancing takes into account the load on the servers dynamically as compared to L4, which can do this only based on connection counts and round robin.
If a server behind a group is busy, all other servers are also tried before failing over to the next group. In the case of L4, when a server that the managed device is talking to is busy, the entire L4 group is marked as busy.
All the certificate-related issues with an L4 switch is not applicable for a server group.
Ease of configuration and use.
For more information on how to configure server groups, see the ZENworks Primary Server and Satellite Reference.
The second means of load balancing is to use a Layer-4 switch. In this scenario, you deploy a network load balancer (hardware or software) and then manually define an L4 switch object in the closest server list. When defining an L4 switch, you specify a DNS or IP address and the ZENworks servers that are being front-ended by the switch. When the agent receives the information, it will attempt to contact the L4 switch any time it wants to talk to one of the servers behind the switch. In this configuration if one of the servers is too busy or unavailable, it is the responsibility of the switch to find the most usable server and send the packet to that server.
Following are the two properties which can be configured in osp-configuration.properties for any DNS/IP:
The osp-configuration.properties is available in the following location:
On Windows: %ZENSERVER_HOME%\conf\security\osp
On Linux: /etc/opt/microfocus/zenworks/security/osp
com.microfocus.osp.l4.addresses: This is used to add any Load Balancers/Reverse Proxies/API Gateway/ IPV4/IPV6/FQDN/ address.
com.microfocus.osp.additional.hostnames: This can be used to add any additional hostnames assigned to the ZCC server.
Both these properties behaves in the same way and supports comma separated list of address and optionally port number.
Example: com.microfocus.osp.l4.addresses=10.10.10.10, 10.10.10.10:8443, [::1]:8443
For more details on L4 switch configuration, see the Support for L4 Switches
in the ZENworks Primary Server and Satellite Reference. Not all ZENworks features currently support L4 switches.