In the virtual enterprise, storage is the new highway – and speed bump
- By Rutrell Yasin
- May 25, 2012
The desktop is imploding.
Cloud infrastructures, IT virtualization and the proliferation of mobile phones and tablets are leaving less and less of the traditional desktop technology intact.
And for good reason: New technologies are rapidly enabling virtual desktop infrastructures (VDI) that promise to lower the cost of agency desktop computing, increase security and make the desktop more agile. New virtual desktop machines allow multiple users to maintain their own personal desktops while sharing the resources of a single computer or server located in a central location.
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That’s the upside. The pain sets in when organizations try to scale to hundreds or thousands of desktops, experts say. If storage is not properly deployed, for example, virtual desktop infrastructures can also cause a lot of heartache.
As these VDI projects are moved into production, unpredictable workloads can overwhelm storage devices and cause performance degradation during times of peak traffic.
Demand on server and storage resources can also rise sharply during the booting up of virtual desktops, login, logoff, shutdown, patching of applications or the running of antivirus scans, all functions that have high input/output demand. The resulting “I/O storms,” as they are called, can cause significant storage bottlenecks that can affect VDI performance.
The new IT highway
Today, technology is emerging that can help organizations unclog the bottlenecks by taking various approaches to offloading virtual desktop input/output traffic before it can impact storage.
“I look at storage as the new highway,” said George Teixeira, CEO of DataCore Software, a developer of software that optimizes performance across different storage devices. “When you see a virtual desktop or virtual machine today, that is just the image of a machine, and the way you move it from one place to another is actually over a storage network.”
The question, Teixeira said, is whether that highway is reliable and fast enough to move and deliver the machines? Those challenges have magnified the problem of storage as people tend to have an old view of storage and think of it as files or data. What they miss with the virtual revolution is that, “when you boot up your computer, that image is your machine,” he said. “I can move that image from one machine to the next now over storage media.”
The end of storage pools
In the past, the only way you could avoid storage bottlenecks was to oversize your storage pool. “Basically, you would have more spindles or disks than you would need to accommodate the capacity requirements of the environment,” said Joe Brown, president of Accelera Solutions, which works closely with agencies to deploy virtualized environments.
“You would have to put in a significant amount of storage network like a fiber-channel network to support the amount of throughput between the host and storage environment,” Brown said.
Storage performance is measured by data transfer -- megabytes per second -- and number of operations or IOPS. What’s important in VDI is the number of operations rather than data transfer the hosting infrastructure can support.
Fortunately, technology is emerging in the storage market to reduce reliance on back-end storage systems to produce the (OPS a virtual desktop environment needs for optimal performance, Brown noted.
Agencies considering VDI should do their homework and understand the total number of IOPS their virtual desktops will consume, Brown advises. To do that, they will have to analyze how their existing desktops are reacting to today’s workloads, Brown said.
There are analysis tools and virtualization experts that can help agencies gain a better understanding of their virtual environments, he added. For example, virtualization vendor VMware offers the Desktop Reference Architecture Workload Code, a tool that helps organizations determine the readiness of any given environment to run virtual desktops.
Off-loading I/O traffic
There are currently a number of different tools and techniques for addressing the VDI storage bottleneck challenge.
Storage optimization technology from Atlantis Computing solves the bottleneck problem by offloading virtual desktop I/O traffic before it affects storage. When the Microsoft Windows operating system and applications send I/O traffic to storage, Atlantis ILIO, a software-based appliance, intercepts and intelligently de-duplicates all traffic before it reaches storage.
Atlantis ILIO processes up to 90 percent of Windows I/O requests in memory so the VDI environment requires less storage to operate with the same performance of physical PCs. Atlantis ILIO supports major hypervisors from Citrix and VMware, any type of storage for VDI and controls how Microsoft Windows operating system interacts with VDI storage.
Some of Atlantis Computing’s federal users include the U.S. Army Medical Command, Marine Corps., Navy Medical Corps. and the National Geospatial Intelligence Agency.
Atlantis is well suited for agencies that are already running virtual desktop environments and have discovered problems with the number of IOPS they are getting from their storage system, Accelera’s Brown said. They can plug it in, begin to take advantage of it and not invest in additional hardware, he said.
Move workloads to most suitable devices
DataCore’s SANsymphony V software optimizes different types of storage by automatically choosing between fast and expensive devices, such as solid state disks and lower-cost but higher-capacity storage resources. The software provides automated storage tiering that monitors I/O behavior, determines the frequency of use, then moves blocks of information to the most suitable classes of storage devices.
“We talk about ourselves as a storage hypervisor,” Teixeira said, noting that the company uses the same concept as VMware or Microsoft Hyper-V server hypervisors. Hypervisors allow multiple operating systems to run concurrently on a host.
“One of the big advantages of a hypervisor is that it is software that is independent of the hardware and gives the user the choice of hardware interchangeability," he said. There is a need for portable software that can work across different models, he added.
DataCore’s software is similar to Atlantis ILIO technology in the sense that it speeds up storage performance, said Steve McMurray, an IT consultant specializing in virtualization. The software runs on a hardware controller or server that sits between the virtualization software such as VMware and the back-end storage.
However, the software does a lot more than accelerate performance, it virtualizes back-end storage, replicates data, offers high availability and mirroring and is tiered based on user profile, McMurray said.
Integrated cache removes complexity
NetApp is a traditional enterprise storage company that has increasingly enhanced its FAS storage controllers to operate in the next-generation data centers.
NetApp uses Flash Cache technology to improve I/O throughput without adding more high-performance disk drives. The approach of distributing workloads is sound, said Mike Giesler, senior director of systems engineering at NetApp. However, NetApp integrates Flash Cache into its storage controllers to take out a layer of complexity and management. As such, it becomes an integrated, high-performance element of the storage infrastructure, Giesler said.
Flash Cache modules can be used to improve performance for workloads that are random read intensive, such as file services, messaging, online transaction processing databases and server/desktop virtualization. Flash Cache can also be used with SATA drives for many workloads to increase storage capacity while maintaining a high level of performance, he said.
Accelera has been doing quite a bit of work with NetApp in virtualized environments within government agencies, Brown noted. Accelera’s solutions architects have engineered NetApp technology to maximize the amount of IOPS their storage devices can produce. NetApp’s Flash Cache and latest version of clustering software on its storage arrays have helped produce a significant number of IOPS, Brown said.
“We’re able to get the number of IOPS needed out of their storage systems. But to drive the cost down on a solution, we will introduce something like an Atlantis solution that helps to minimize the reliance on the storage subsystem,” Brown said.
Virtualization without a SAN
Virtual storage firm Nutanix aims to virtualize data centers without requiring a SAN, according to CEO Dheeraj Pandej. To that end, the company has built a Google-like storage architecture that combines computing and storage on the same server node.
“The real problem is that compute and storage are very far apart – four or five hops away," Pandej said. Instead of building a cheaper, faster storage box, Nutanix brings the storage into the compute gear, creating a massively parallel architecture, he said.
Nutanix Complete Cluster is a cluster of high-performance server nodes each running a standard VMware hypervisor, complete with processors, memory and local storage, including solid state drives and hard drives.
Each server node runs virtual machines just like a standard virtual
machine host. Local storage from all servers is virtualized into a unified pool so a VM can write data anywhere in the cluster and is not limited by storage on the server in which it is running.
Two use cases are for VDI – desktops in the cloud -- and on battleships or on the battlefield in vehicles such as hummers or helicopters where there are network constraints, Pandej said.
Nutanix can offload virtual desktop I/O traffic and alleviate storage bottlenecks, Accelera’s Brown noted. “If you were in the process of building a new environment, scaling up your environment or refreshing the server host, that would be a good time to bring in Nutanix,” Brown advised, adding “because it is a piece of hardware that would replace some of the compute resources you already have.”
Brown noted that emerging products such as Atlantis’ ILIO and Nutanix are actually being deployed in government settings. And since they can lower the cost of storage as well as boost performance for virtual desktop users, more agencies might consider VDI deployments, experts say.
Many organizations have thought that moving from physical to virtual desktops would save money only to find that storage for VDI can be costly, sometimes paying hundreds of thousands of dollars on storage, DataCore’s Teixeira said.
A lot of VDI installations in government are in pilot stages now, but larger deployments could occur in 2013, Teixeira said, noting that the hold back for full deployment has been storage. “The cost of storage has made it less practical,” he said.