Benefits of virtualization
Resource optimization,
efficient management,
cost savings
Virtualization type
APP: XenApp, VMware ThinApp
Program library: WINE
Operating system: Docker, FreeBSD jail, OpenVZ
Computer hardware: VMWare, Xen, Virtual PC
The difference between full virtualization and paravirtualization
XEN supports two modes of full virtualization and paravirtualization. The difference between the two lies in whether the operating system layer needs to be modified.
Vmware system can be divided: Vmware Work Station, vsphere / vcenter, exsi / exs
| Full Virtualization | Para Virtualization |
|---|---|
| Virtual Box、 VMware Workstation、Vmware EXSI/EXS、 XenServer | Xen |
 |
 |
| Unmodified virtualization system, such as EXSI | Modified operating system, such as centos + xen |
- Full Virtualization: Hardware-assisted virtualization technology (Intel-VT, AMD-V) hardware-assisted virtualization technology is required. The operating system code does not need any modification natively, and the performance is average.
- Para Virtualization: No hardware-assisted virtualization technology is required, but the guest operating system code needs to be modified to include virtualization code, and the performance is higher. "Parallel virtualization" refers to how the communication between the guest operating system and the hypervisor improves performance and effectiveness Sex.
Paravirtualization is more efficient and faster than full virtualization, and provides performance close to that of unvirtualized systems. Such as centos + xen
Software-assisted and hardware-assisted virtualization in full virtualization
As shown in the figure, Ring0 is the core instruction layer. The core instruction right of software-assisted virtualization is in the host operating system, such as Window10 with VMware Workstation installed, and the hardware-assisted virtualization is that the virtual host (Guest OS) owns the core instruction.
| Software-assisted virtualization | Hardware-assisted virtualization |
|---|---|
 |
 |
| The core command right of software-assisted virtualization is in the host operating system, such as Window10 with VMware Workstation installed | In hardware-assisted virtualization, the virtual host (Guest OS) owns the core command right |
Important function
The following features are not supported by all free virtualization platforms.
Multi Server Management with XenCenter GUI：多服务器图形化管理
Active Directory Integration：AD域集成
Dynamic Memory Control：内存动态控制
Live Memory VM Snapshot and Revert：快照热恢复
Live VM Migration：服务器热迁移
Scheduled Snapshots：定时快照
XenServer Conversion Manager：虚拟化服务迁移管理（P2V）
Maximum Pool Size：最大资源池
Distributed Virtual Switch Controller：交换机虚拟化
Comparison of three different architectures
Citrix XenServer
VMWare EXSI
VMWare vSphere
Future Trends
Docker+KVM+OpenStack
