Today’s highly mobile workforce demands seamless access to the data, applications and services that people need to get the job done – from any location and across multiple client devices. Virtual desktop infrastructure (VDI) is an effective way to provide this access, offering a consistent, secure end-user experience designed to increase productivity and business agility.

Traditionally, high upfront CAPEX associated with a VDI rollout has always been its Achilles’ heel. Centralizing hundreds or thousands of stand-alone desktops into a data center translates into lots of infrastructure needs – particularly servers and storage.

The problem is exacerbated if you want to start small and scale in small increments. Why? Suppose your solution includes a SAN that can support up to 1,000 desktops. If you start at 500 desktops, you still need that one SAN. Your ROI is sub-optimal until your environment grows to 1,000 desktops. And then when you need to grow to 1,200 desktops, you need another unit of that SAN which remains sub-optimal until the deployment grows to 2,000 desktops. You get the picture.

The new Dell XC Series Web-scale Converged Appliances, which begin shipping next week, change that.

XC Series appliances integrate Dell’s proven x86 server platform and Nutanix web-scale software to provide an enterprise-class converged infrastructure solution for VDI environments. These appliances consolidate compute and storage into a single appliance enabling VDI rollout to be easily expanded – one appliance at a time – delivering linear and predictable scale-out growth with pay-as-you-grow flexibility.

The modular building-block design of XC Series enables IT organizations to start small for their VDI deployments and then grow incrementally up to many thousands of users. Nutanix Distributed File System (NDFS) runs on each appliance, aggregating direct-attached storage resources (Flash and HDDs) across all appliances. With advanced data tiering and local Flash storage speeding user application response times, other software-delivered storage services like thin provisioning, compression and deduplication provide storage capacity savings – a key requirement for a successful, cost-effective VDI deployment.

So if you are deploying 500 desktops, you have 5 of these XC Appliance nodes supporting your VDI environment for all the compute and storage needs. When you plan to grow to 600 desktops, just add another XC Appliance node to the existing environment and you are all set. Start small and scale at the pace of your business, that’s the power of XC Series appliances for VDI.

What about SAN?

Does the converged appliance spell the end of SAN for VDI? No, not at all. There are many scenarios where a SAN could be the best choice for your VDI deployment. For example, if you prefer to have best-of-breed VDI infrastructure components optimized for your specific VDI environment resulting in the lowest possible cost per desktop, or you need to grow storage independent of compute and vice versa, or you want best enterprise-class storage features like advanced tiering, you would likely be looking at SAN solutions.

To that end, we have been bolstering our SAN portfolio to cover all of the VDI use cases for our customers.

We have recently introduced a new, small footprint Dell Storage SC4020 array that leverages proven Dell Compellent technology to provide an automated, self-tuning storage system capable of efficiently scaling to satisfy VDI production level workloads. Specifically, SC4020 uses Flash-optimized Data Progression to tier data across high-endurance, high-performance, write-intensive SSDs and higher capacity, lower cost, read-intensive SSDs. This significantly drives down the storage-per-virtual-desktop cost while providing the required high performance in VDI deployments.

As an example, we created a 1,800 user persistent desktop VDI architecture using Citrix XenDesktop 7.5 with Citrix Machine Creation Services (MCS) and Citrix Personal vDisk technology. The solution leverages a single SC4020 All-Flash array with 18 write-intensive SSDs and 6 read-intensive SSDs to deliver very high performance (125,000 IOPS at peak of boot storm, 20-30 IOPS/VM at steady state) at a low storage-per-virtual-desktop cost.

Dell Compellent SC8000 All-Flash arrays are recommended where performance requirements are even higher. This SC8000 VDI reference architecture shows how a 3,000 user persistent desktop can be deployed leveraging Flash-optimized Data Progression between 24 write-intensive SSDs and 18 read-intensive SSDs where the underlying storage platform needed to support very high IOPS per user desktop even at steady state (40+ IOPS/VM in this case).

All-Flash arrays are good, but what happened to Dell’s hybrid arrays?

While Dell Storage SC Series All-Flash arrays provide high performance, Dell Storage PS Series hybrid storage arrays provide optimal balance between performance and capacity needs for many VDI use cases. The PS Series hybrid arrays – built on automated and intelligent data tiering between 7 SSDs and 17 10K SAS HDDs within the same enclosure – can help organizations that are limited by the cost-per-desktop hurdle start their VDI deployment plans much sooner. Moreover, the EqualLogic peer storage scale-out architecture of the PS Series arrays achieves linear scalability of both controller throughput and storage capacity as new arrays are added with the VDI environment growth. This linear scaling in both performance and capacity keeps the storage-per-virtual-desktop cost low even in large VDI deployments.

When we introduced the Dell EqualLogic PS6210XS hybrid arrays last December, we showcased a 2,000 desktop VMware Horizon View based VDI deployment on a single PS6210XS array. The reference architecture demonstrated how the array with 7 SSDs (800GB capacity each) and 17 10K SAS HDDs (1.2TB capacity each) delivered the optimal capacity and performance (~10 IOPS/VM at steady state) for the VDI solution.

Today, we are adding a new Dell Storage PS4210XS hybrid array to the VDI solutions portfolio. The PS4210XS array has half of the capacity (7 SSDs, 400GB capacity each and 17 10K SAS HDDs, 600GB capacity each) and performance of its big brother, PS6210XS, along with a very attractive price to boast about. Smile This new storage reference architecture shows that a single PS4210XS can easily support 1,000 desktop VDI deployments with ~10 IOPS/VM at steady state. Now you can have even lower storage-per-virtual-desktop cost starting from initial rollouts of small number of virtual desktops.

So, which one do I pick?

The answer is, as always, “it depends.” Smile (What else could it be?)

If you want a simple, highly scalable converged solution and need to grow compute and storage together with predictable granular scalability, XC Appliance is for you. If you prefer to have best of breed infrastructure components in your VDI stack and like the advanced capabilities SAN offers, you go the Dell Storage SAN solutions route. Then, you pick between SC Series All-Flash arrays and PS Series hybrid arrays depending on your VDI performance and capacity needs.

No matter what path you take in your VDI journey, we have you covered. That’s the Dell Storage for VDI storyTM.