Ask network admins, and they'll tell you a virtual desktop infrastructure (VDI) can offer enterprises several benefits over traditional PCs--among them, mobility, security and manageability. Then, they'll tell you the barriers they've faced toward VDI adoption--according to InformationWeek Reports' "Informed CIO: VDI Snake Oil Check," they range from the inability to work when disconnected from the network to initial costs and a lack of ROI. And then there's storage.
"The storage most people have for their average SAN can't support the IOPS that are needed for a VDI environment," said Brett Waldman, senior research analyst for cloud and virtualization system software at IDC. For example, enterprises can face what's called a "boot storm," which can occur when most employees arrives at the office in the morning and log in simultaneously.
Storage vendors including Dell, Nimble Storage, GreenBytes and NetApp are responding with products designed to handle the workloads created by VDI:
Dell: The recently introduced EqualLogic PS6510ES and PS6500ES are hybrid storage arrays that combine high-performance SSD and high-capacity near-line SAS drives and come as appliances. They can host up to 85 Tbytes per array and up to 2 petabytes per Dell EqualLogic group, and are designed to handle large data sets serving multiple applications, including VDI implementations, data warehousing and online transactional databases. According to Travis Vigil, executive director of Dell Storage, the PS6510ES improves IOPS performance by 360% and reduces latency by 75% compared with its predecessor, the P6510X.
The PS6510ES and PS6500ES use automated auto-tiering algorithms to determine which applications and data are used most frequently and to store each in an appropriate location. "They offer a combination of high-performance SDD with affordability of near-line SAS, and can help alleviate the performance bottlenecks such as a boot storm," Vigil explains.
He says that enterprises have historically adopted the EqualLogic line to virtualize their data centers, but that Dell is seeing more demand for them to support VDI adoption.
Fusion-io: Flash memory has rapidly found footing in servers and racks as incumbent storage vendors add it to existing product lines, while others have included flash in their architectures from inception.
Fusion-io, an early entry into the server-side flash market, recently announced that NetApp was incorporating the Fusion ioMemory platform to make it compatible with its Data ONTAP operating system.
Tim Russell, VP of NetApp's data lifecycle ecosystem group, says Fusion-io's caching software will play an important role in automatic storage tiering. Automated tiered storage enables a storage device to automatically migrate data from one type of media to another based on how often the data accessed. Similar to tiering, caching actually copies the data to faster media such as SSD rather than moving it from slower, spinning disks.
GreenBytes: Earlier this month, GreenBytes introduced its IO Offload Engine, an appliance that handles the virtual machine booting, provisioning and disk drive swaps from the storage system to speed up VDI implementations. This frees up the SAN to handle lower-priority workloads.
Nimble Storage: Nimble has taken a hybrid approach to its storage architecture support demanding workloads, such as VDI. Its Cache Accelerated Sequential Layout Architecture lays out data by taking random writes coming into the system and writing them on a new location on disk sequentially, making more efficient use of low-cost disk. Meanwhile, data that's accessed often is put on flash.
Ed Lee, lead architect at Tintri, which specializes in virtualization-aware storage, says flash has become critical. "Flash is turning out to be an enabler for VDI," he says. "Before flash, you couldn't get the latencies down low enough to provide users with a responsive experience. "
Lee says VDI adoption often fails because the projects are deployed on an already heavily loaded disk system, resulting in frustrated end users. "It's much more sluggish than their original desktop, so they complain bitterly."
However, a storage infrastructure that incorporates flash doesn't solve all of the performance challenges of VDI, he adds: "As you peel back layers of the onion, flash in itself is probably not sufficient to do a successful, large-scale VDI deployment."
IDC's Waldman says it's important for enterprises to segment their users properly based on their application use, rather than implementing an app for all users in a carte blanche fashion. From a storage perspective, enterprises should consider carving out a portion of their data centers to specifically support VDI requirements.
Veteran Wyse executive Jeff McNaught, now Dell Cloud Client Computing's chief strategy and marketing officer, had another consideration for enterprises: For VDI to be fully implemented across an organization, a broad range of applications must be supported on a variety of endpoints, including thin clients, PCs, smartphones and tablets. "In a properly architected virtualized environment, the endpoint does not matter," he says.
