Sunday, January 1, 2012

Using Ganglia to monitor virtual machine pools

The Ganglia charts show virtual machine performance metrics collected using sFlow. Enabling sFlow monitoring on each node in a virtual machine pool provides a highly scalable solution for monitoring performance. Embedded sFlow monitoring in the hypervisors simplifies deployments by eliminating the need to poll for metrics. Instead, virtual machine metrics are pushed directly from each node to the central Ganglia collector. Currently sFlow agents are available for XCP (Xen Cloud Platform), Citrix XenServer and KVM/libvirt virtualization platforms, see In addition, an sFlow agent has been demonstrated for the upcoming Windows 8 version of Hyper-V.

The article, Ganglia 3.2 released, describes the basic steps needed to configure Ganglia as an sFlow collector. Once configured, Ganglia will automatically discover and track new servers and virtual machines as they are added to the network.

Note: To try out Ganglia's sFlow/virtual machine reporting, you will need to download Ganglia 3.3.

By default, Ganglia will automatically start displaying the virtual machine metrics. However, there is an optional configuration setting available in the gmond.conf file that can be used to modify how Ganglia handles the sFlow virtual machine metrics.

  accept_vm_metrics = yes

Setting the accept_vm_metrics flag to no will cause Ganglia to ignore sFlow virtualization metrics.

Ganglia and sFlow offers a comprehensive view of the performance of a virtual machine pools, providing not just virtualization related metrics, but also the server CPU, memory, disk and network IO performance metrics needed to fully characterize pool performance.

Note: Visibility into network performance is an essential part of managing a virtual machine pool since virtual machines rely on the network for storage, local communication and Internet access. Network performance also affects other critical pool operations like virtual machine migration and backup. Support for the sFlow standard by most switch vendors delivers the necessary end to end network visibility and further simplifies management by including the network in an integrated monitoring solution.

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