1.6.6 Monitoring the network resources

This subsection explains how to monitor the network resources of a KVM system.

Organization of this subsection

(1) Overview
(2) Monitoring examples

(1) Overview

In a KVM system, multiple virtual machines share the NIC of the physical server. The NIC allocated to each virtual machine is called the virtual NIC.

The OS running on a virtual machine recognizes a virtual NIC as a normal NIC.

In a virtual environment, virtual machines use the physical NIC at the same time, and as a result, the network bandwidth that can be used by each virtual machine becomes narrow. Consequently, each virtual machine's network data send/receive speed may decrease.

By monitoring the network's performance data, you can detect such performance deterioration of the virtual machine, and thus you can take the necessary corrective action.

The two records described below are used for monitoring the network resources. For details about the records, see 5. Records.

PI_HNI record

This record is used to monitor the performance data of the physical NIC.
PI_VNI record

This record is used to monitor the performance data of the virtual NIC.

The figure below shows the range of performance data collected in each record.

Figure 1‒64: Correspondence between records and data collection ranges

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(2) Monitoring examples

Using resource monitoring of virtual NIC1 and NIC2 and physical NIC1 and NIC2 as an example, this subsection explains problems that may occur with network resources, and how to solve them. The figure below shows the items monitored here and the flow of actions to take.

Figure 1‒65: Monitored items and flow of actions

(a) Example of monitoring the data send/receive speed of a virtual NIC

The load placed on a virtual NIC can be evaluated from the data send/receive speed of the virtual NIC. You can check the data send/receive speed of the virtual NIC in the Rate field of the PI_VNI record.

The figure below shows an example of monitoring the data send/receive speed of a virtual NIC.

Figure 1‒66: Example of monitoring the data send/receive speed of a virtual NIC

Monitoring template report to be checked: VM Network Data

In this example, the value that indicates the data send/receive speed for virtual NIC 2 is large. This means that virtual NIC 2 is heavily loaded. If there are virtual NICs that are heavily loaded, depending on the communication status of the virtual machine, take either of the following actions:

If the virtual machine communicates with an external network

Add physical NICs to distribute the load on virtual NICs.
If the virtual machine communicates with only other virtual machines in the same virtual environment

Creates a virtual switch for the internal network, and change the NIC that is connected to the other virtual machines.

(b) Example of monitoring the data send/receive speed of a physical NIC

The load on a physical NIC can be evaluated from the data send/receive speed of the physical NIC. You can check the data send/receive speed of the physical NIC in the Rate field of the PI_HNI record.

The figure below shows an example of monitoring the data send/receive speed of a physical NIC.

Figure 1‒67: Example of monitoring the data send/receive speed of a physical NIC

Monitoring template report to be checked: Host Network Data

In this example, the data send/receive speed of physical NIC2 is high, indicating a high load level. If there is a physical NIC with a high load, consider adding a physical NIC.

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