Welcome!

SDN Journal Authors: Pat Romanski, Patrick Hubbard, Elizabeth White, Sven Olav Lund, Liz McMillan

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.

@CloudExpo Stories
SYS-CON Events announced today that Avere Systems, a leading provider of hybrid cloud enablement solutions, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Avere Systems was created by file systems experts determined to reinvent storage by changing the way enterprises thought about and bought storage resources. With decades of experience behind the company’s founders, Avere got its ...
Today most companies are adopting or evaluating container technology - Docker in particular - to speed up application deployment, drive down cost, ease management and make application delivery more flexible overall. As with most new architectures, this dream takes significant work to become a reality. Even when you do get your application componentized enough and packaged properly, there are still challenges for DevOps teams to making the shift to continuous delivery and achieving that reducti...
We all know that end users experience the Internet primarily with mobile devices. From an app development perspective, we know that successfully responding to the needs of mobile customers depends on rapid DevOps – failing fast, in short, until the right solution evolves in your customers' relationship to your business. Whether you’re decomposing an SOA monolith, or developing a new application cloud natively, it’s not a question of using microservices – not doing so will be a path to eventual b...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
As you move to the cloud, your network should be efficient, secure, and easy to manage. An enterprise adopting a hybrid or public cloud needs systems and tools that provide: Agility: ability to deliver applications and services faster, even in complex hybrid environments Easier manageability: enable reliable connectivity with complete oversight as the data center network evolves Greater efficiency: eliminate wasted effort while reducing errors and optimize asset utilization Security: imple...
High-velocity engineering teams are applying not only continuous delivery processes, but also lessons in experimentation from established leaders like Amazon, Netflix, and Facebook. These companies have made experimentation a foundation for their release processes, allowing them to try out major feature releases and redesigns within smaller groups before making them broadly available. In his session at 21st Cloud Expo, Brian Lucas, Senior Staff Engineer at Optimizely, will discuss how by using...
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 lead...
The session is centered around the tracing of systems on cloud using technologies like ebpf. The goal is to talk about what this technology is all about and what purpose it serves. In his session at 21st Cloud Expo, Shashank Jain, Development Architect at SAP, will touch upon concepts of observability in the cloud and also some of the challenges we have. Generally most cloud-based monitoring tools capture details at a very granular level. To troubleshoot problems this might not be good enough.
Companies are harnessing data in ways we once associated with science fiction. Analysts have access to a plethora of visualization and reporting tools, but considering the vast amount of data businesses collect and limitations of CPUs, end users are forced to design their structures and systems with limitations. Until now. As the cloud toolkit to analyze data has evolved, GPUs have stepped in to massively parallel SQL, visualization and machine learning.
SYS-CON Events announced today that CAST Software will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CAST was founded more than 25 years ago to make the invisible visible. Built around the idea that even the best analytics on the market still leave blind spots for technical teams looking to deliver better software and prevent outages, CAST provides the software intelligence that matter ...
The next XaaS is CICDaaS. Why? Because CICD saves developers a huge amount of time. CD is an especially great option for projects that require multiple and frequent contributions to be integrated. But… securing CICD best practices is an emerging, essential, yet little understood practice for DevOps teams and their Cloud Service Providers. The only way to get CICD to work in a highly secure environment takes collaboration, patience and persistence. Building CICD in the cloud requires rigorous ar...
SYS-CON Events announced today that Daiya Industry will exhibit at the Japanese Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Ruby Development Inc. builds new services in short period of time and provides a continuous support of those services based on Ruby on Rails. For more information, please visit https://github.com/RubyDevInc.
When it comes to cloud computing, the ability to turn massive amounts of compute cores on and off on demand sounds attractive to IT staff, who need to manage peaks and valleys in user activity. With cloud bursting, the majority of the data can stay on premises while tapping into compute from public cloud providers, reducing risk and minimizing need to move large files. In his session at 18th Cloud Expo, Scott Jeschonek, Director of Product Management at Avere Systems, discussed the IT and busine...
As businesses evolve, they need technology that is simple to help them succeed today and flexible enough to help them build for tomorrow. Chrome is fit for the workplace of the future — providing a secure, consistent user experience across a range of devices that can be used anywhere. In her session at 21st Cloud Expo, Vidya Nagarajan, a Senior Product Manager at Google, will take a look at various options as to how ChromeOS can be leveraged to interact with people on the devices, and formats th...
First generation hyperconverged solutions have taken the data center by storm, rapidly proliferating in pockets everywhere to provide further consolidation of floor space and workloads. These first generation solutions are not without challenges, however. In his session at 21st Cloud Expo, Wes Talbert, a Principal Architect and results-driven enterprise sales leader at NetApp, will discuss how the HCI solution of tomorrow will integrate with the public cloud to deliver a quality hybrid cloud e...
SYS-CON Events announced today that Yuasa System will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Yuasa System is introducing a multi-purpose endurance testing system for flexible displays, OLED devices, flexible substrates, flat cables, and films in smartphones, wearables, automobiles, and healthcare.
Is advanced scheduling in Kubernetes achievable? Yes, however, how do you properly accommodate every real-life scenario that a Kubernetes user might encounter? How do you leverage advanced scheduling techniques to shape and describe each scenario in easy-to-use rules and configurations? In his session at @DevOpsSummit at 21st Cloud Expo, Oleg Chunikhin, CTO at Kublr, will answer these questions and demonstrate techniques for implementing advanced scheduling. For example, using spot instances ...
DevOps is under attack because developers don’t want to mess with infrastructure. They will happily own their code into production, but want to use platforms instead of raw automation. That’s changing the landscape that we understand as DevOps with both architecture concepts (CloudNative) and process redefinition (SRE). Rob Hirschfeld’s recent work in Kubernetes operations has led to the conclusion that containers and related platforms have changed the way we should be thinking about DevOps and...
SYS-CON Events announced today that Taica will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Taica manufacturers Alpha-GEL brand silicone components and materials, which maintain outstanding performance over a wide temperature range -40C to +200C. For more information, visit http://www.taica.co.jp/english/.
When it comes to cloud computing, the ability to turn massive amounts of compute cores on and off on demand sounds attractive to IT staff, who need to manage peaks and valleys in user activity. With cloud bursting, the majority of the data can stay on premises while tapping into compute from public cloud providers, reducing risk and minimizing need to move large files. In his session at 18th Cloud Expo, Scott Jeschonek, Director of Product Management at Avere Systems, discussed the IT and busine...