(image from Anatomy of an open source cloud)
A cloud data center consists of large numbers of physical servers, each running a hypervisor with one or more virtual switches connecting the physical network to virtual machines (see Anatomy of an open source cloud). An integrated approach to network and system management is required in order to manage performance in this environment (see Management silos).
The combination of sFlow in Open vSwitch and Host sFlow provide a lightweight, scalable, performance monitoring solution for open source virtualization (Xen, XenServer and KVM) and cloud platforms (OpenStack and Xen Cloud Platform). However, coordinating and managing the configuration of sFlow monitoring of the large number of virtual switches and virtual machines in a cloud data center is a complex task that needs to be addressed as part of a scalable monitoring solution.
In order to address this challenge, the latest version of the Host sFlow agent adds the ability to automatically configure sFlow on the Open vSwitch. The Host sFlow agent already includes a highly scalable configuration mechanism (see DNS-SD) and the integration with the Open vSwitch extends this mechanism to configure network and system performance monitoring throughout the cloud.
Referring back to the diagram, the sFlow standard provides a performance monitoring solution that spans all the elements of the cloud. Most physical networking devices already include sFlow support (see Multi-vendor support), providing visibility into network and storage activity. Open vSwitch and Host sFlow extend visibility to include virtual networking and physical/virtual server performance respectively. Thus, sFlow provides the integrated end-to-end view of performance needed to manage resources throughout the cloud (see sFlow Host Structures).