1. ECS understanding:
Server distributed cluster (a large number of computing resources, storage resources) + Xen virtualization (integrated use of resources) = resource units can be flexibly adjusted (single server -> Xen elastic computing unit) integrated into a "huge virtual resource pool", through elastic Calculate and allocate nodes, generate a large number of virtual, available "virtual hosts" -> load balancing to dynamically allocate these virtualized resources to achieve the theoretical maximum use of hardware resources.
"Cloud": Viewed as a huge pool of virtual resources (such as hardware, development platforms or services) that are easy to use and access, and these resources can be dynamically configured according to changes in load (scale) to make optimal use of resources.
2. Introduction of application technology
XEN virtualization technology (provides elastic computing)
Xen Software Layer: Virtual Machine Monitor, an open source project of the University of Cambridge Computer Laboratory. The software layer that runs directly on the computer hardware to replace the operating system , it can run multiple guest operating systems (Guest OS) concurrently on the computer hardware .
Xen supports x86, x86-64, Itanium, Power PC and ARM processors, so Xen can run on a large number of computing devices, currently Xen supports Linux, NetBSD, FreeBSD, Solaris, Windows and other commonly used The operating system runs on its hypervisor as a guest operating system.
Xen's virtualization of virtual machines is divided into two categories, para virtualization and full virtualization (Hardware VirtualMachine).
Paravirtualization (Paravirtualization) Some materials are called "paravirtualization", referred to as PV, which is a virtualization technology dominated by Xen. This technology allows the virtual machine operating system to perceive itself as running on the Xen Hypervisor (system hypervisor) rather than directly on the hardware, while also identifying other guest virtual machines running in the same environment.
Full virtualization (Hardware Virtual Machine), also known as "hardware virtualization", referred to as HVM, means that the virtual machine running on the virtual environment always feels that it is running directly on the hardware during the running process, and cannot perceive Virtual technology for running other virtual machines in the same hardware environment.
Windows virtual machines virtualized on Xen must be fully virtualized.
3. Features
Large-scale: Cloud computing services are usually provided by cluster systems running in multiple data centers, and each data center node can reach tens of thousands, providing massive computing and storage resources for various applications.
Low cost: Cloud computing provides users with scalable resources through resource virtualization, supports various types of applications to run in the system at the same time, improves overall resource utilization, and reduces costs.
High reliability: Cloud computing can store user data in multiple copies, and user data will not be lost if any physical machine is damaged. The design of multiple data centers also meets the needs of disaster recovery.