Virtualization has been a true facilitator in enterprise data centers. Server
virtualization has brought savings in the form of a reduced space and increased efficiency of the physical server, with low fuel consumption. It also slowed down the time to market for the development and deployment of applications.
Virtualization is the foundation for cloud computing. Organizations looking for a day migrate all your data center to the cloud-based resources to reach the goal of 100% virtualization.
During VMworld 2015, VMware two engineers discuss the challenges with up to 100% virtualization. I will summarize its findings.
Non-technical Factors:
Before jumping to the technical difficulties to achieve 100% virtualization in a data center, it is appropriate to recognize non-technical challenges. These challenges have not been addressed in the framework of the session of VMworld.
Business drivers such as the licensing of software prohibited costs may prevent some workloads to be virtualized. For example, some software company charges a licensing fee based on the number of steps in a group of virtualization. Therefore, if you have a cluster of 32 nodes with 4-socket node, you will be charged fees for 128 basins.
Another technique driver may not be the size of the workload. An application requires the same amount of computing resources as their VM Host largest, would be prohibitively expensive to virtualize the application. For example, a large database server consumes 96 GB of RAM, and increased VM Host has 96 GB of physical RAM. The benefits of virtualization can not exceed the cost of adding a hypervisor overload the workload.
The last obstacle is not technical policy issues surrounding the mission-critical applications. Even in the current climate, there is a perception by some that mission-critical applications require hardware implementations bare metal.
Sharpen your Environment:
VMware vSphere says he's fine tuned for workloads generalized; It 'been my experience that this is more or less true. Therefore, if a customer is experiencing poor performance in a virtualized workload, the first place to look is the development of two hosts and virtual machine hosts. A common configuration errors is the subsystem I / O engineers must first look at the storage and network settings on both the VM Host and the guest operating system.
Always follow the best practices for configuring host I / O Some of the best practices of VMware, along with some of my, are:
• make sure the driver is used vmxnet3 VM guest;
• install the latest version of VMware Tools;
• disable unnecessary services;
• Virus Protection Harnessing the whole series against individual VM based; is
• secure storage multi-path is set up and working.
While these tips will go a long way for most workloads, more complex systems require advanced optimizations. The typical workloads that are performance problems when virtualized include high performance computing (HPC) applications and large data.
Virtualization Tax:
It would be unrealistic to think that the abstraction that allows the benefits of virtualization does not have a cost. The hypervisor adds a layer of latency for each operation of CPU and I / S. The stronger the performance of the application requires more impact on latency.
VMware has provided advanced optimizations that reduce the impact of this hypervisor overheads; these tools have improved in all versions of vSphere. Most of the optimizations have come in the form of exposing the physical subsystems for guest operating systems.
Remote Direct Memory Access (RDMA) is a generic term to facilitate access to physical hardware directly to a virtual machine. VMware offers three types of access technologies RDMA:
• DirectPath E / S (supported in vSphere 4.0 and higher);
• SR-IOV (supported in vSphere 5.1 and higher); is
• vRDMA (expected in vSphere 6.0 Update 1).
I will give an example of one of the three optimizations. DirectPath E / S takes advantage of
virtualization extensions Intel VT-d and AMD-Vi. DirectPath E / S network allows direct access to the network interface card to a server (NIC). Direct access means that the VM can take advantage of the advanced features of high-end package downloads NIC. In a test of performance, VMware has shown that a high-traffic web server could accommodate 15% more users per CPU to allow DirectPath front of a virtual network adapter traditional.
However, these optimizations have direct access costs. Activation DirectPath E / S for the network to a virtual machine off the advanced features such as vSphere vMotion. VMware is working on technologies that allow direct hardware access without sacrificing features.
Conclusion:
Workloads may question the desire to achieve 100% virtualization within the data center. While VMware has closed the gap in the most demanding workloads, it may still be impractical to virtualize some workloads.
