2.3.18 Data that can be collected with virtualized systems that use VMware/KVM

(1) VMware/KVM functionality

Like other virtualized systems, VMware/KVM provides the following functionality:

• Virtual networks

• Virtual processors

• Virtual memory

• Virtual disks

VMware/KVM manages combinations of the above functionality to create a virtual machine (VM). The created VM is recognized as a single host from other hosts, and can be treated the same as a physical machine.

Because multiple VMs can be created and run, operating systems like Linux and Windows can run concurrently.

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(2) VMware/KVM configuration

VMware/KVM implements a virtualized system by creating a distinction between a host OS and a guest OS.

To set up a virtualized system:

1. Install Windows, Linux, or another OS on the actual hardware.

2. Install VMware/KVM on the installed host OS.

   Here, the OS on which VMware/KVM is installed is called the host OS.

3. Use VMware/KVM to create a VM.

   Install other operating systems on the created VM. An operating system installed on the VM is called a guest OS.

As shown above, VMware/KVM uses a parent/child configuration to implement a virtualized system, in which the guest OS is executed on the host OS.

One feature of VMware is that a specialized custom OS is used as the host OS instead of Windows or Linux. In other words, VMware implements a virtualized system in which Windows or Linux is running on a specialized custom OS.

Depending on the type of VMware/KVM, the host OS can also be Windows or Linux instead of the custom OS.

Figure 2‒13: VMware configuration

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(3) Using PFM - Agent for Platform on VMware/KVM

Keep the following in mind when using PFM - Agent for Platform on VMware/KVM.

Installing PFM - Agent for Platform

To use PFM - Agent for Platform, install it on the guest OS. Because the host OS for VMware is a custom OS optimized to implement virtualized systems with VMware, operation of applications is not guaranteed.

Processor information

In a virtualized system, if sufficient resources are not allocated to the host OS, the impact will extend to the operation of the host OS. In particular, the impact is significant on processor resources. If overload occurs, it might be difficult to determine whether the processor resources allocated to the VM are insufficient, or whether the host OS processor resources are insufficient.

VMware/KVM also has a feature that allows upper and lower limits to be set for processor usage allocation, which can cause wide swings in usage because resource switching is automatically performed within the set range.

If this seems to be the case, monitor items that are not easily impacted by dynamic changes to processor resources, such as the current queue length.

Memory

Be careful when setting an alarm for memory as a resource that can be changed dynamically. Even when the amount of used memory is fixed, if the allocated memory resources are reduced, memory usage will grow, and could cause alarms to be reported unintentionally.

Devices

Disk performance data is collected only for logical partition groups on the guest OS. System-wide performance data including the host OS cannot be collected. For the network adapter information, information about virtual network adapters allocated to the guest OS is obtained.

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