Why You Can’t Virtualize Without Flash Storage

June 18, 2012 5 Comments »
Why You Can’t Virtualize Without Flash Storage

A comprehensive virtualization strategy for the modern data center is no longer an option or a convenience—it’s now a strategic imperative. As the technology has matured, the benefits have moved beyond higher server utilization, consolidation and cost reductions to enable agility and flexible services. Although initial virtualization gains were focused on the server, Virtualized Desktop Infrastructure (VDI) is becoming a reality. But while over 50 percent of data center server applications are virtualized, the figure is closer to 15 percent for desktops. Clearly there are still roadblocks to overcome in order to achieve a fully virtualized data center.

In a similar fashion, it’s becoming a data center imperative to replace disk-based storage with flash memory arrays to support the demands of a virtualized environment. Traditional disk-based storage is often the Achilles heel of a virtualization initiative. When a large number of physical systems are consolidated into virtual machines, the storage I/O requirements can overwhelm mechanical disks from a latency and bandwidth perspective. This consolidation problem is compounded by the highly random nature of VM I/O. Flash-based primary storage certainly eliminates the performance bottlenecks, but as with the evolution of virtualization technology, it delivers a storage infrastructure that is more flexible, reliable and cost effective.

The business benefits of VDI can be grouped into four categories:

  1. Centralized Management: Deploying, updating and maintaining management are centralized for efficiency and deliver the end user a much higher service level.
  2. Security and Compliance: Centralization and standardization vastly simplify the process of creating a secure and compliant infrastructure. Variability is reduced, vulnerabilities can be more easily discovered, and security patches can be rolled out rapidly to the entire organization.
  3. End-User Experience: Faster response times (lower latency) and higher bandwidth ensure more-responsive applications and end-user productivity.
  4. IT Agility: This is a key objective in nearly any IT initiative and directly affects end-user productivity. Requests for new desktops and new software can be completed in hours rather than days. Operating system upgrades that might cost millions of dollars to perform with traditional desktops can be accomplished in a fraction of the time at a fraction of the cost.

Standing in the way of those benefits are three key challenges to VDI rooted in the fact that disk-based storage advancements have not kept pace with the Moore’s Law improvements in compute and networking power. Organizations have been forced to overprovision disk drives and rely on techniques such as short-stroking and other “unnatural acts of storage.” Many of these issues are compounded with VDI:

Random I/O Contention: The highly random nature of desktop I/O places a huge strain on disk—this makes sense, as every time a piece of data needs to be accessed a platter needs to rotate and a head needs to seek it out. Write operations commonly represent over 80 percent of the total I/O. The combination of a large number of virtual desktops and highly random I/O can severely affect performance.

Bandwidth requirements: Desktop environments and applications are increasingly taking advantage of rich media capabilities such as audio and video. Although these operations are primarily sequential and friendlier to disk drives, they need significant I/O bandwidth. In a multi-user environment this can cripple performance.

Boot and Logon/Logoff Storms: This occurs when many virtual desktops are accessed simultaneously—for example, at the beginning of the work day. The spike in I/O can easily overwhelm a storage system if it’s not designed to handle the extra load. If an IT organization provisions storage for a peak load that only happens 10–20 percent of the time, it’s a significant waste of resources.

Flash memory arrays address these challenges with highly reliable, high-performance shared network storage. By delivering hundreds of thousands, or up to a million, IOPS per system, flash memory arrays can handle boot storms with ease. Large multi-user environments can be supported with multiple systems deployed as shared network storage. Flash arrays offer latency performance under 200 microseconds, delivering rapid boot and login times at any scale. Flash arrays eliminate the slow response times of disk as well as spikes of slow latency, ensuring a consistent end-user experience. Single systems can offer over 4GB/s of bandwidth and can be aggregated to support even the most demanding multimedia applications.

Most importantly flash memory arrays deliver flexible and agile storage to maximize the benefits of virtualization. More enterprise applications and desktops can be virtualized with storage roadblocks removed.

About the Author

As Vice President of Product Management, Narayan Venkat leads Violin Memory’s strategy to build a portfolio of scalable flash storage systems to accelerate the adoption of flash for business-critical applications, big data analytics and virtualization. Before Violin, Narayan was the VP of Cloud Infrastructure at VMware, where he led the company’s storage initiatives for the vSphere virtualization platform. Before joining VMware, he was VP and business line director for the Engenio Storage Group at LSI Corporation and product strategy leader for NetApp’s NAS, SAN and storage management solutions.

Photo courtesy of brewbooks

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