Virtual Desktop Infrastructure (VDI) is poised to provide a new management and deployment model for end-user computing by centralizing physical desktops to virtualized desktop farms in the data center. The resulting environment offers increased manageability, enhanced security and data protection, while providing new capabilities such as anywhere, anytime access for teleworkers. The risk, of course, lies in end-user performance expectations and the return on investment (ROI).
Ideally, a VDI solution will provide an equal or better end-user experience than a physical desktop while keeping the deployment cost at par or lower than desktop deployment costs. If these objectives are met, the significant operational cost savings will support an immediate migration toward VDI for the majority of organizations.
The Challenges with Desktop Computing
The traditional model of desktop computing has been to deploy a thick client PC, one machine per user. In this client-server compute model, the PC is a workhorse, with dedicated CPU, hard drive, video card, display, operating system, etc. This approach does allow for fewer servers in the datacenter, a very good multimedia experience, and flexibility.
The thick client set up makes operating system updates and patch management one of the most difficult aspects of a desktop solution. Software management, application hot fixes, and upgrades are necessary for addressing bugs, providing enhancements, and addressing security vulnerabilities. But with traditional desktops, each PC has its own operating system and applications, and must be updated individually, a large drain on IT staffing resources.
Force 3 Reference Architecture: Virtual Desktop Infrastructure
The Force 3 VDI reference architecture has two major goals:
- To provide a better end-user experience than physical desktops
- Provide direct cost savings against physical desktops
These goals are accomplished with two key components:
In a typical VDI deployment, storage input/output (IO) becomes a major performance bottleneck, and therefore a major contributor to a negative end user experience. By centralizing the desktop loads, VDI combines the IO requirements of individual desktops into a centralized storage system. Even though the average user IO load can be 5-8 IOPS (IOs per second), the peak IOPS can range from 20 to 100 IOPS on a centralized platform. So during peak IO, such as morning login and evening logoff, the storage system should be able to handle the peak IO for all of the users at the same time, with little effect on the end user.
The Force 3 architecture solves the Storage IO issue by using flash array as the storage for desktop VM OS images. Flash array can offer very high IOPS at low latency. Even under heavy load, flash array provides consistent performance characteristics rather than an exponential performance degradation experienced by spinning disks. The FalconStor/Violin flash array used in Force 3’s architecture can provide up to 200,000 IOPS and 20TB of SLC NAND storage in a 3U unit.
Flash array, while providing great performance, is inherently more expensive than traditional spinning disks. To optimize the solution cost, the Force 3 architecture employs several mechanisms to reduce the flash array space requirements. The key components of the storage optimization include:
Utilization of VMware View Composer Linked Clone VMware Linked Clone uses writable snapshot technology to reduce the space requirement for a virtual machine deployment. Only changes to the master desktop image are stored on the Linked Clone storage
Placement of permanent user data to network storage via Folder Redirection and Persistent Disk By placing user persistent disk and VM swap file on a non-flash array storage and re-directing user data via folder redirection, the flash array storage requirement can be further reduced.
Regular refresh of desktop A high-performance flash array backend enables fast desktop refreshes. Regular desktop refreshes clean out the linked clone storage.
Disabling VM suspension A disabling virtual machine suspension feature removes requirements for suspend files for each VM in flash array storage.
2.Graphics and Multi Media Experience
Remote display protocol, which can provide quality graphics and a multi-media experience, is key to end user acceptance of the VDI solution. VMware View PC over IP (PCoIP) delivers a rich user experience over IP network with progressive build, bi-directional audio, and USB redirection in a completely new protocol.
To characterize the behavior of the VDI environment under heavy IO load, Force 3 performed storage stress testing on the Force 3 architecture-based VDI system. The stress testing was performed at the Force 3 Customer Innovation Center. Results showed superior performance and significant cost savings.
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