XenServer uses a very extensive and powerful open source Xen system management program. Xen is an open industry standard virtualization technology and the "engine" of many companies' commercial virtualization products, including Citrix, Symantec, Oracle, Red Hat, Novell, Sun, Stratus, Marathon, Egenera, FusionSphere, Neocleus And Phoenix Technology. In addition, Amazon Elastic Cloud, the world's largest public cloud service provider, has adopted the Xen system management program. These cases have fully verified the scalability and nature of the major Xen technology.
XenServer provides a complete virtual infrastructure solution, including a hypervisor with real-time function migration, full-featured management, and various tools needed to migrate applications, desktops, and server physical environments to virtual environments. Advanced management functions, availability, integration functions or automation functions can provide comprehensive data center automation, advanced integration and management, and key performance characteristics.
Control Domain (or Domain0) is a Linux virtual machine with a higher priority than the guest operating system. Control Domain manages the network and storage I/O of all guest VMs, and because it uses Linux device drivers, A wide range of physical devices can be supported.
The Xen hypervisor (Hypervisor) is a thin layer of software running on the hardware. Xen allows each physical server to run an abstraction layer of one or more "virtual servers", effectively separating the OS and its applications from the underlying hardware.
The hardware layer contains physical server components (including memory, CPU, and disk drives)
Linux virtual machine: It includes paravirtualized kernel and drivers (Guest OS needs to be modified accordingly). Access storage and network resources through Control Domain, and access CPU and memory through the Xen control interface on the hardware.
Windows virtual machine: It uses paravirtualized drivers to access storage and network resources through Control Domain. Xen is designed to take full advantage of the virtualization capabilities of Intel VT and AMD-V processors. Hardware virtualization can realize high-performance virtualization of the Windows kernel without using traditional simulation technology.
XenServer management framework
Enterprise version XenServer4.0 and later introduced the concept of resource pool. Users can manage multiple virtualized servers as a single entity through the resource pool. To achieve centralized management, without the need to log in to all XenServer. All servers share a common network and storage framework.
The resource pool adopts a master/slave high-availability server management model, and all pool configuration information is synchronized to all slave servers. Ensure business continuity in the event of a failure of the main server without causing any fatal failures.
XenCenter can connect and manage multiple servers and resource pools; XenCenter Client serves as a graphical management console to connect to XenServer servers to manage virtual machines and resources.
XenServer storage architecture
Support IDE, SATA, SCSI and SAS local storage and shared storage such as iSCSI, Fibre Channel and NFS due to its open storage management interface.
XenServer provides StorageLink technology, integrates with storage such as NetApp, Dell/EqualLogic, and IBM, and provides direct access to external storage (SAN/NAS) APIs, so that you can make full use of various optimized advanced storage services, including fast cloning, LUN Technologies such as zeroing, thin allocation, snapshot and copy deletion.
XenServer's network architecture
XenServer's network can be connected to external physical network interfaces, or a single server, or all virtualized networks in the pool. After installing XenServer on a physical server, the system will create a network for each physical network card on the server.
Virtual Network Card (NIC):
Each virtual machine can be configured with one or more virtual network cards, each of which has its own IP and MAC address. The virtual machine looks like an independent physical system on the network.
After XenServer 6.0, the Open vSwitch virtual switch under the Apache license is adopted by default. Currently, virtualization platforms that use Open vSwitch include KVM, VritualBox, OpenStack, OpenQRM, OpenNebula, etc.
The virtual network card can be connected to a virtual switch that realizes network isolation. Each virtual switch can be connected to a physical network through a physical network card, or it can be configured as a full virtual network, providing a speed comparable to memory for traffic from dedicated virtual machines to virtual machines.
Virtual machines can be bound to separate VLANs, thereby isolating the traffic between virtual machines from the traffic of other physical servers, reducing network load, improving security, and simplifying the reconfiguration process.
Through distributed switches, users can uniformly create and manage a multi-tenant, isolated and flexible network, and provide a secure and state-based migration environment for virtual machines. The distributed virtual switch supports ACL, Netflow, network status monitoring and other functions.