Cost Justifying Flash For VDI Storage

Virtual Desktop Infrastructures (VDI) make a big promise to the data center manager; to substantially drive down the cost of supporting user desktops and laptops while increasing the security for them. But for a VDI project to be successful the users have to accept it and it has to fit within the IT budget. The storage savior to this challenge is flash. Implementing flash in the VDI storage infrastructure means that users experience flash-like performance in their virtual desktops, which immediately helps with adoption. The key is making the “math” of flash work so that the hard cost of its implementation doesn’t exceed the potential operational cost savings.

Desktop Density is Key

Justifying flash for a virtual desktop infrastructure means fully leveraging that investment so that the price per desktop makes sense, while assuring that users get the exact desktop experience they want. Since VDI hosts are the most expensive part of the VDI infrastructure, using flash to drive up the number of VMs per VDI server is the quickest way to reduce total infrastructure cost. If a flash based storage system can provide better desktop performance but reduce the number of hosts by 50% then the total cost of the VDI infrastructure may be less than a comparable hard drive storage array.

Flash Provides Painless Data Efficiency

Thin Provisioning, Deduplication, Compression and Cloning are all attributes of data efficiency. Each of them extracts a toll from performance by either increasing write overhead or storage controller overhead. But with flash, there is typically enough extra performance that these features can all be enabled without any noticeable performance impact. This is critical because each of these features drives down the cost of storage, something that’s especially important in flash based systems. And VDI provides an excellent return on that data efficiency investment.

A hybrid system should extend all these data efficiency techniques to the hard disk tier, especially deduplication and compression. While the cost savings per GB is not as impressive on that tier, data reduction effectively creates extra capacity that’s, essentially free. Also, if the system correctly keeps metadata for deduplication in flash then the performance impact, even on disk, is largely mitigated.

More Than Just VDI

Another key advantage to a flash based system is leveraging the excess performance and capacity they provide to sustain workloads other than just VDI, including virtual servers and bare metal databases. Extending the number and types of workloads on the system allows the flash investment to be shared, lowering the cost allotted to the VDI project and thereby lowering the storage cost per desktop. Consolidating storage systems also reduces storage management time, training and simplifies the data protection process. The result is a system brought in to allow a VDI project to deliver operational efficiency can also bring operational efficiency to other environments like virtual server infrastructure and database applications.

All-Flash or Hybrid?

The case for flash in a VDI environment is compelling. The next step is to decide between an all-flash array or a hybrid array. The advantage an all-flash array has is that it essentially eliminates all performance tuning and could potentially support a greater number and mix of workloads. For data centers with the budget dollars available, all-flash arrays may represent the shortest path to value.

Hybrid arrays, while less expensive per GB, can add to the storage management burden because decisions need to be made about the ratio of flash to spinning disk and which data sets should be manually pinned to flash storage. But if a large enough flash area is purchased then the accuracy of the flash tier improves and the need to manually lock certain data sets into flash is reduced. Vendors that can provide that flash tier at a reasonable price point make hybrid an easier option by allowing the purchase of flash tiers that represent 25% of the total data set. In these situations, the chances of a tier miss are almost zero.

In addition, some hybrid arrays can provide Block and NAS services on the same system. This “unified” capability gives them an even greater chance to consolidate workloads. Many VDI environments end up using a block storage system for virtual machines images and Network Attached Storage (NAS) for user data. A hybrid array that can provide unified block and file can then consolidate virtual machine images and user data storage onto a single system. This further reduces the cost of the system and, of course, simplifies the environment.

Sponsored By Tegile Systems

Tegile Systems makes both All-Flash and Hybrid arrays that are feature rich. This allows their customers to select the type of flash solution that makes the most sense for their specific data center. Tegile’s storage arrays also include data efficiency techniques like deduplication and compression, making them ideal for virtualized desktop and server environments. Most importantly their storage arrays provide both file and block services, which allows a VDI project to be supported by a single storage system that provides rapid access to virtual machine images and a cost effective storage area for user data.

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Eleven years ago George Crump founded Storage Switzerland with one simple goal; to educate IT professionals about all aspects of data center storage. He is the primary contributor to Storage Switzerland and is a heavily sought after public speaker. With over 25 years of experience designing storage solutions for data centers across the US, he has seen the birth of such technologies as RAID, NAS and SAN, Virtualization, Cloud and Enterprise Flash. Prior to founding Storage Switzerland he was CTO at one of the nation's largest storage integrators where he was in charge of technology testing, integration and product selection.

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