The manager report
The manager function of Load Balancer calculates a weight for each server. These weights are used to determine how many connections a server should receive as compared with the other servers in the same cluster and port configuration. Understanding the manager report is critical to understanding how the network traffic is distributed.
- Active connections (ACTV) or CPU (in the case of Site Selector component based on input from the Metric Server)
- New connections (NEWC) or Memory (in the case of Site Selector component based on input from the Metric Server)
- Port Load (PORT)
- System load (SYS)
- Active connections (ACTV)
- Active connections are TCP connections that are closed at the start of the manager cycle.
- New connections (NEWC)
- New connections represent the increase in total connections from the start of the manager cycle to the start of the last manager cycle.
- Port Load (PORT)
- The port load is the value that is obtained from an advisor that
is defined on this cluster:port combination. If an advisor is not
started, the port load is always zero. When an advisor is defined,
the port load typically represents the number of milliseconds for
the advisor to receive a response from the server.When the port load is shown as -1, the advisor did not receive a successful response to its query. Increase the log level and log size for the advisor to investigate why the server did not respond. If the server never responds to the connection request, complete the following steps:
- Ensure that you can successfully ping the server from the Load Balancer machine.
- Verify that the server application is started and listening on the port that is defined. The server should be listening on the wildcard address (0.0.0.0), or both the cluster IP address and the real server IP address to successfully respond to the advisor requests.
- System load (SYS)
- The system load represents the value that is returned from the
metric server. If metrics have not been added for this cluster:port
combination, the system load is zero (0). When metrics are defined,
the system load is a value in between -1 and 100, which represents
the status of the server. 100 is very busy and zero (0) is idle.If the system load shows -1, Load Balancer cannot communicate with the metric server on the back-end machine. Ensure Load Balancer keys are properly distributed to the server, that the server can be pinged from the Load Balancer, and that metric server is started on the machine. If the problem persists, complete the following steps:
- Edit the script for the metric server on the back-end machine and increase both the log level and log size.
- Restart the metric server.
- Increase the the log size and the log level for the metric monitor at the Load Balancer.
- Examine the log files on both the Load Balancer machine and the back-end machine to determine why communication is failing.
- CPU and Memory (Site Selector component)
- The CPU and Memory represent the values that are returned from
the metric server . Cpuload and memload metrics are added automatically
for the Site Selector configuration. CPU and Memory are values in
between -1 and 100, which represent the status of the server. 100
is very busy and zero (0) is idle. If these metrics show -1, Load
Balancer cannot communicate with the metric server on the back-end
machine. Ensure Load Balancer keys are properly distributed to the
server, that the server can be pinged from the Load Balancer, and
that metric server is started on the machine. If the problem persists,
complete the following steps:
- Edit the script for the metric server on the back-end machine and increase both the log level and log size.
- Restart the metric server.
- Increase the log size and the log level for the metric monitor at the Load Balancer.
- Examine the log files on both the Load Balancer machine and the back-end machine to determine why communication is failing.
The number of active connections and new connections are determined based upon the number of connections that the executor has forwarded within the last cycle of the last manager function. The manager cycle is two seconds, by default.
Configuring server weights
Under normal circumstances, Load Balancer uses all of the values that have proportions that are not zero to calculate the new weight. For example, if the proporations are 40 40 20 0, the active connections and new connections are 40% of the weight calculation each and the port load is 20%.
ACTV NEWC PORT SYS
Server1 50 200 25 0
Server2 25 100 50 0
The initial
weight calculations will be:- Server1 = .40(50) + .40(200) + .2(25) = 20 + 80 + 5 = 105
- Server2 = .40(25) + .40(100) + .2(50) = 10 + 40 + 10 = 60
- Server1 = (105/165) * 10 = 6
- Server2 = ( 60/165) * 10 = 4
If the port load or the system load is -1, and the respective proportion for the port or system column is greater than 0, the calculated weight is zero (0). Zero (0) indicates that the server is not active and new requests are not sent to the server.
If you quiesce a server, you will see that the weight is also shown as zero (0), but the port load is positive if the server is still online. If a quiesced server goes offline, the port load is -1.
If a user issues a "server down" function on a server to prevent Load Balancer from sending requests to that server, the weight is -1 regardless of the value for the port load and system load.