Significance of a complete virtualization solution

Translated from the original article "the benefits of parameter alizing networking and storage": Bernd
Harzog

VMWare, Microsoft, red hat, and Citrix have already virtualized the CPU and memory in their respective virtualization layers. VMware went on to propose the concept of a software-defined data center to extend virtualization technology to network and storage. What is the significance of Virtualization of these resources? What are the benefits for users? What are the special values of virtual network and storage compared with virtualized CPU and memory? This is definitely worth thinking about.

CPU Virtualization

Looking back, if we define CPU virtualization as an abstract physical CPU to facilitate the use of computing resources by workload, VMWare is not the first provider to implement CPU virtualization, modern Operating Systems have long been achieved. The load includes threads and processes, and the operating system is responsible for scheduling these threads and processes to the CPU for running.

VMware uses the CPU virtualization technology to solve the problem of Running multiple applications in an operating system instance. The difficulty in implementing this task lies in the close dependency between each application and the operating system. An application can only run on a specific version of the operating system and middleware. This is what Windows users often refer to as "DLL hell ". Therefore, most users can run only one application on a Windows operating system instance, and the operating system instance exclusively occupies one physical server. This situation will cause the CPU resources of the physical server to be greatly wasted. Enabling multiple operating system instances to run on one physical server at the same time is the value of the CPU virtualization technology provided by VMware. The integrated server makes full use of CPU resources, which can bring great benefits to users.

The benefits of server integration can be achieved only when the workload does not need to know that they are sharing the CPU. The virtualization layer must have this capability. This is a difference between CPU virtualization and other virtualization modes.

Memory Virtualization

VMware's CPU virtualization achieves CPU sharing through time slices. Sharing memory via virtualization technology is not that easy. Assume that an application requires 2 GB physical memory. Even if 2 GB virtual memory is allocated to it, the corresponding physical memory will also exist. Otherwise, the performance of the application will become poor (using disk swap memory pages ). VMware uses transparent page sharing technology to achieve a certain degree of Memory Sharing. The virtualization layer identifies the same part of the read-only memory area (code page) of each operating system. These pages only keep one copy in the memory. Most of the memory used by the Windows operating system is the code page. Therefore, vsphere only keeps one copy of the Windows operating system on physical servers running n windows instances. This is why in a VDI environment, you only need to allocate much less memory to the physical desktop than the VDI image.

It should be emphasized that the CPU time slice can be implemented by the virtualization layer, but the memory cannot be sharded by time. Multiple applications can share one CPU, but multiple applications cannot use a memory area at the same time. The CPU speed continues to grow, and the density of virtual machines is mainly limited by the number of physical memory on the server.

Network Virtualization

After talking about the history of virtualization technology, let's look at the future. One of the main problems we face now is how network virtualization works and what benefits can it bring us? The answer to this question is almost like this: Network virtualization moves the configuration of the virtual network from the hardware switch to the virtualization platform. The virtualization administrator can easily create and change virtual networks. The network configuration can also easily move with the virtual machine. Cloud management software can automatically create the virtual network required by the workload based on the Service Catalog. This is similar to the benefits that the virtualization layer can easily configure virtual CPU and virtual memory. However, in terms of cost saving and improved ROI, it is not as obvious as the benefits of server integration.

However, network virtualization is also unique in CPU virtualization and memory virtualization. It transfers some work implemented by network hardware to virtual network software. VMware has already implemented vswitches in software for a long time. Microsoft's hyper-V also has something similar. The two virtual machines running on the same host need to communicate with each other, and network traffic does not need to be transmitted to the physical switch through the physical Nic. If you place the web server, application server, and database server serving an application on the same host. Only the traffic of the database server flows through the NIC (using NAS) or memory card (using fiber-optic storage). Therefore, network virtualization can reduce the number of network ports required by the physical server. Can this be called "network integration? Reducing the network cable by 1/3 to half (and Tor switch ports) is also a major achievement.

It has more profound significance and value to move the control right and switch device itself to the software. Users no longer need expensive and Intelligent switches. All intelligence has been moved into the software. Who else needs a smart switch? You only need a dumb switch that can forward data packets. Network virtualization technology will change the switch industry. These two points can explain what Cisco reflected when VMware acquired nicira.

Storage Virtualization

Unlike CPU virtualization, storage virtualization is not the main investment target of VMware or Microsoft. A variety of abstract physical storage methods have long been applied. Lun is a logical abstraction. The storage Administrator is responsible for ing it to physical storage. Some innovative enterprises such as tintri and virsto also create value by providing unique storage abstraction technologies.

To understand the value of VMware's software-defined data center, we must first introduce what the storage virtualization technology will look like. VMware now has a product named vsphere storage appliance that can integrate local hard disk storage of up to three physical servers into a pool. This virtual storage pool can be accessed through an access point, provides redundancy and high-availability services. If VMware
What if the storage appliance is extended to a 32-node server cluster? Provides storage virtualization services for 32-node clusters. If the server has enough disks to accommodate data, and the virtual storage array can meet the storage performance requirements of applications, you may not need to purchase NAS or fiber optic storage. If VMware implements the above idea, what benefits will Storage Virtualization increase on the basis of CPU, memory, and network virtualization? The answer may be:

Similar to memory, this method of virtual storage does not allow multiple loads to share the same storage area. If a load requires 2 TB network storage, it means that a 2 TB local storage pool is required. So there will be no obvious integration benefits like CPU virtualization and server virtualization.

However, management benefits are obvious. Managing these local storage device pools is much easier than managing high-end arrays of EMC and netapp. The key lies in whether the local storage pool can provide performance similar to that of high-end arrays.

If these local storage pools can replace network and optical fiber storage arrays, they will bring benefits similar to network virtualization. Local direct connection storage of servers is much cheaper than shared storage on the network. If this technology can be applied to a large number of VMware customers, the cost savings in storage will be significant.

 

 

This article Reprinted from: http://blog.sina.com.cn/s/blog_6b67f82b01019t4g.html