Welcome!

Open Source Cloud Authors: Liz McMillan, Dana Gardner, Pat Romanski, Kevin Benedict, Darren Anstee

Related Topics: Containers Expo Blog, Microsoft Cloud, Open Source Cloud, @CloudExpo, Cloud Security, SDN Journal

Containers Expo Blog: Article

Can You Trust VDI Storage Benchmarks?

The truth behind VDI benchmarks

by George Crump, Storage Switzerland

VDI (Virtual Desktop Infrastructure) implementation projects are going to be priorities for many IT Managers in 2013 and a key concern will be end-user acceptance. If the users don't embrace their virtual desktops they won't use them and the project is doomed to failure. The key to acceptance is to provide users with an environment that feels the same, performs better and is more reliable than their current stand-alone system. The storage system bears most of the responsibility in delivering that experience.

IT managers who want to capitalize on the opportunity that the virtual desktop environment can focus on two key capabilities when they evaluate storage system vendors. The first is being able to deliver the raw performance that the virtual desktop architecture needs and the second is doing so in the most cost effective way possible. These are two capabilities that are traditionally at odds with each other and not always well-reflected in benchmark testing.

For most organizations the number-one priority for gaining user acceptance is to keep the virtual desktop experience as similar to the physical desktop as possible. Typically, this will mean using persistent desktops, a VDI implementation in which each user's desktop is a stand-alone element in the virtual environment for which they can customize settings and add their own applications just like they could on their physical desktop.

The problem with persistent desktops is that a unique image is created for each desktop or user, which can add up to thousands of images for larger VDI populations. Obviously, allocating storage for thousands of virtual desktops is a high price to pay for maintaining a positive user experience.

In an effort to reduce the amount of storage required for all of these images, virtualized environments have incorporate features such as thin provisioning and linked clones. The goal is to have the storage system deliver a VDI environment that's built from just a few thinly provisioned ‘golden' VDI images, which are then cloned for each user.

As users customize their clones, only the differences between the golden image and the users' VDIs need to be stored. The result is a significant reduction in the total amount of storage required, lowering its overall cost. Also, the small number of golden images allows for much of the VDI read traffic to be served from a flash-based tier or cache.

When a write occurs from a thinly provisioned, cloned virtual desktop more has to happen then just the operation to write that data object. The volume needs to have additional space allocated to it (one write operation), the metadata table that tracks unique branches of the cloned volume has to be updated (another write operation) and some sort of parity data needs to be written, depending on the RAID protection in place. Then, finally, the data object is written. This entire process has to happen with each data change no matter how small.

Herein lays the tradeoff in using these features. While reducing the amount of space required for the VDI images, thin provisioning and cloning increase the demand for high write performance in the storage system. This presents a significant opportunity for storage system vendors who can address these new performance requirements.

Many storage systems that use a mix of flash memory and hard disk technology don't use the higher performing flash for writes; they use it for actively reading data. While these storage systems have storage controllers designed to handle high read loads, the increased write activity generated by thin provisioning and cloning is still going to relatively slow hard disk drives. Because this type of I/O traffic is highly random, the hard drives are constantly "thrashing about". Basically the controller sits idle while it waits for the hard disk to rotate into position to complete each write command. Even systems with an SSD tier or cache may have problems providing adequate performance because they too don't leverage the high speed flash for write traffic.

Due to the high level of thin provisioning and cloning, plus the fact that once a desktop is created a large part of its I/O is write traffic, many cached or tiered systems do not perform well in real-world VDI environments and can provide misleading VDI Benchmark scores.

The Truth Behind VDI Benchmarks
Most VDI Benchmarks focus primarily on one aspect of the VDI experience, the time it takes to boot a given number of virtual desktops. The problem with using a "boot storm test" is that this important but read-heavy event is only a part of the overall VDI storage challenge. During most of the day desktops are writing data, not reading it. In addition, simple activities such as logging out and application updates are very write-intensive. The capability of a storage system to handle these write activities is not measured by many VDI benchmarking routines.

A second problem with many VDI benchmarking claims is that for their testing configuration they do not use thinly provisioned and cloned volumes. Instead, they use thick volumes in order to show maximum VDI performance.

As discussed above, in order to keep user adoption high and costs low most VDI implementations would preferentially use persistent desktops with thin provisioning and cloning. Be wary of vendors claiming a single device can support over 1000 VDI users. These claims are usually based on the amount of storage that a typical VDI user might need as opposed to the Read/Write IOPS performance they will most likely need.

Trustworthy VDI Performance
A successful VDI project is one that gains end-user acceptance while reducing desktop support costs. The cost of a storage system that can provide thin provisioning, cloning and an adequate sized flash storage area to support the virtual environment could be too high for some enterprises to afford.  And, an additional cost could be incurred with the performance problems that are likely to appear after the initial desktop boot is completed because of the high level of write I/O.

The simplest solution may be to deploy a solid state appliance like Astute Networks ViSX for VDI. These devices are 100% solid state storage to provide high performance on both reads AND writes. This means that boot performance is excellent and performance throughout the day is maintained as well.

With a solid state based solution to the above problems, performance will not be an issue, but cost may still be. Even though it can provide consistent read/write performance throughout the day for a given number of virtual desktops, the cost per desktop of a flash based solution can be significantly higher than a hard drive based system.

However, it's likely in larger VDI environments (400+ users) that flash-based systems are really the only viable alternative to meet the performance requirements which can easily exceed 100 IOPS per user. Fortunately, flash-based systems can also produce efficiencies that bring down that cost in addition to the well-known benefits of using 1/10th the floor space, power and cooling compared to traditional storage systems.

First, the density of virtual desktops per host can be significantly higher with a flash appliance. And, the system is unaffected by the increase in random I/O as the density of virtual machines increases.

Second, the speed of the storage device compensates for the increased demands of thin provisioning and cloning operations run on the hypervisor. These data reduction services can now be used without a performance penalty. This means that the cost of a storage system with a more powerful storage controller and expensive data services like thin provisioning and cloning can be avoided.

Finally, the flash appliance is designed to tap into more of the full potential of solid state-based storage. For example, Astute uses a unique DataPump Engine protocol processor that's designed to specifically accelerate data onto and off of the network and through the appliance to the fast flash storage. This lowers the cost per IOPS compared to other flash-based storage systems.

Most legacy storage systems use traditional networking components and get nowhere near the full potential of flash. In short, the appliance can deliver better performance with the same amount of flash memory space. This leads to further increases in virtual machine density and space efficiency because more clones can be made - resulting in very low cost per VDI user.

Conclusion

VDI benchmark data can be useful but the test itself must be analyzed. Users should look for tests that not only focus on boot performance but also performance throughout the day, and at the end of the day. If systems with a mix of flash and HDD are used then enough flash must be purchased to avoid a cache miss, since these systems rarely have enough disk spindles to provide adequate secondary performance.

A simpler and better performing solution may be to use a solid state appliance like those available from Astute Networks. These allow for consistent, high performance throughout the day at a cost per IOPS that hybrid and traditional storage vendors can't match. Their enablement of the built-in hypervisor capabilities, like thin provisioning, cloning and snapshots, also means that they can be deployed very cost effectively.

>

George Crump is lead analyst of Storage Switzerland, an IT analyst firm focused on the storage and virtualization segments.

More Stories By Derek Kol

Derek Kol is a technology specialist focused on SMB and enterprise IT innovations.

@ThingsExpo Stories
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, wh...
Video experiences should be unique and exciting! But that doesn’t mean you need to patch all the pieces yourself. Users demand rich and engaging experiences and new ways to connect with you. But creating robust video applications at scale can be complicated, time-consuming and expensive. In his session at @ThingsExpo, Zohar Babin, Vice President of Platform, Ecosystem and Community at Kaltura, will discuss how VPaaS enables you to move fast, creating scalable video experiences that reach your...
In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, provided an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life sett...
Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is expected in the amount of information being processed, managed, analyzed, and acted upon by enterprise IT. This amazing is not part of some distant future - it is happening today. One report shows a 650% increase in enterprise data by 2020. Other estimates are even higher....
SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.
19th Cloud Expo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterpri...
Businesses are struggling to manage the information flow and interactions between all of these new devices and things jumping on their network, and the apps and IT systems they control. The data businesses gather is only helpful if they can do something with it. In his session at @ThingsExpo, Chris Witeck, Principal Technology Strategist at Citrix, will discuss how different the impact of IoT will be for large businesses, expanding how IoT will allow large organizations to make their legacy ap...
In his general session at 18th Cloud Expo, Lee Atchison, Principal Cloud Architect and Advocate at New Relic, discussed cloud as a ‘better data center’ and how it adds new capacity (faster) and improves application availability (redundancy). The cloud is a ‘Dynamic Tool for Dynamic Apps’ and resource allocation is an integral part of your application architecture, so use only the resources you need and allocate /de-allocate resources on the fly.
SYS-CON Events announced today the Enterprise IoT Bootcamp, being held November 1-2, 2016, in conjunction with 19th Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA. Combined with real-world scenarios and use cases, the Enterprise IoT Bootcamp is not just based on presentations but with hands-on demos and detailed walkthroughs. We will introduce you to a variety of real world use cases prototyped using Arduino, Raspberry Pi, BeagleBone, Spark, and Intel Edison. Y...
The vision of a connected smart home is becoming reality with the application of integrated wireless technologies in devices and appliances. The use of standardized and TCP/IP networked wireless technologies in line-powered and battery operated sensors and controls has led to the adoption of radios in the 2.4GHz band, including Wi-Fi, BT/BLE and 802.15.4 applied ZigBee and Thread. This is driving the need for robust wireless coexistence for multiple radios to ensure throughput performance and th...
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devices - comp...
The many IoT deployments around the world are busy integrating smart devices and sensors into their enterprise IT infrastructures. Yet all of this technology – and there are an amazing number of choices – is of no use without the software to gather, communicate, and analyze the new data flows. Without software, there is no IT. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists will look at the protocols that communicate data and the emerging data analy...
According to Forrester Research, every business will become either a digital predator or digital prey by 2020. To avoid demise, organizations must rapidly create new sources of value in their end-to-end customer experiences. True digital predators also must break down information and process silos and extend digital transformation initiatives to empower employees with the digital resources needed to win, serve, and retain customers.
“We're a global managed hosting provider. Our core customer set is a U.S.-based customer that is looking to go global,” explained Adam Rogers, Managing Director at ANEXIA, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York City, NY.
Smart Cities are here to stay, but for their promise to be delivered, the data they produce must not be put in new siloes. In his session at @ThingsExpo, Mathias Herberts, Co-founder and CTO of Cityzen Data, will deep dive into best practices that will ensure a successful smart city journey.
Why do your mobile transformations need to happen today? Mobile is the strategy that enterprise transformation centers on to drive customer engagement. In his general session at @ThingsExpo, Roger Woods, Director, Mobile Product & Strategy – Adobe Marketing Cloud, covered key IoT and mobile trends that are forcing mobile transformation, key components of a solid mobile strategy and explored how brands are effectively driving mobile change throughout the enterprise.
In this strange new world where more and more power is drawn from business technology, companies are effectively straddling two paths on the road to innovation and transformation into digital enterprises. The first path is the heritage trail – with “legacy” technology forming the background. Here, extant technologies are transformed by core IT teams to provide more API-driven approaches. Legacy systems can restrict companies that are transitioning into digital enterprises. To truly become a lea...
DevOps at Cloud Expo, taking place Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long dev...
The Jevons Paradox suggests that when technological advances increase efficiency of a resource, it results in an overall increase in consumption. Writing on the increased use of coal as a result of technological improvements, 19th-century economist William Stanley Jevons found that these improvements led to the development of new ways to utilize coal. In his session at 19th Cloud Expo, Mark Thiele, Chief Strategy Officer for Apcera, will compare the Jevons Paradox to modern-day enterprise IT, e...
What happens when the different parts of a vehicle become smarter than the vehicle itself? As we move toward the era of smart everything, hundreds of entities in a vehicle that communicate with each other, the vehicle and external systems create a need for identity orchestration so that all entities work as a conglomerate. Much like an orchestra without a conductor, without the ability to secure, control, and connect the link between a vehicle’s head unit, devices, and systems and to manage the ...