saravananlinux

Refer:- http://docs.cloudstack.apache.org/en/master/concepts.html#what-is-apache-cloudstack What is Apache CloudStack? Apache CloudStack is an open source Infrastructure-as-a-Service platform that manages and orchestrates pools of storage, network, and computer resources to build a public or private IaaS compute cloud. With CloudStack you can: Set up an on-demand elastic cloud computing service. Allow end-users to provision resources Cloud Infrastructure Overview Resources within the cloud are managed as follows: Regions: A collection of one or more geographically proximate zones managed by one or more management servers. Zones: Typically, a zone is equivalent to a single datacenter. A zone consists of one or more pods and secondary storage. Pods: A pod is usually a rack, or row of racks that includes a layer-2 switch and one or more clusters. Clusters: A cluster consists of one or more homogenous hosts and primary storage. Host: A single compute node within a cl...

Emulated devices Emulated devices, sometimes referred to as virtual devices, exist entirely in software. Emulated device drivers are a translation layer between the operating system running on the host (which manages the source device) and the operating systems running on the guests. T he device level instructions directed to and from the emulated device are intercepted and translated by the hypervisor. Any device of the same type as that being emulated and recognized by the Linux kernel is able to be used as the backing source device for the emulated drivers.  Para-virtualized Devices Para-virtualized devices require the installation of device drivers on the guest operating system providing it with an interface to communicate with the hypervisor on the host machine. T his interface is used to allow traditionally intensive tasks such as disk I/O to be performed outside of the virtualized environment. Lowering the overhead inherent in virtualization in this manner is intended to a...

A VLAN (Virtual LAN) is an attribute that can be applied to network packets. Network packets can be "tagged" into a numbered VLAN. A VLAN is a security feature used to completely isolate network traffic at the switch level. VLANs are completely separate and mutually exclusive. T he Red Hat Enterprise Virtualization Manager is VLAN aware and able to tag and redirect VLAN traffic, however VLAN implementation requires a switch that supports VLANs. At the switch level, ports are assigned a VLAN designation. A switch applies a VLAN tag to traffic originating from a particular port, marking the traffic as part of a VLAN, and ensures that responses carry the same VLAN tag. A VLAN can extend across multiple switches. VLAN tagged network traffic on a switch is completely undetectable except by machines connected to a port designated with the correct VLAN. A given port can be tagged into multiple VLANs, which allows traffic from multiple VLANs to be sent to a single port, to be deci...