There's a lot of information out there about conventional models for managing storage for VDI, but new technologies...
that can reshape how IT administrators think about virtual desktop infrastructure are always emerging. In the VDI storage market, the latest players are software-only.
Some people make the mistake of thinking all the vendors in this market are the same. Indeed, they typically do one of two things: accelerate existing storage or create a virtual storage area network (SAN) from a disk that's already in the hosts. Once a vendor is put into one of these two buckets, it's easy to dismiss them as "just another acceleration or vSAN provider."
The truth is that most of the new vendors in the VDI storage market are different from one another.
Who's making waves in the VDI storage market
The obvious elephant in the room is VMware's Virtual SAN, which aggregates and accelerates disk that is already in the host. It converts hard drives into a resilient virtual SAN where the VMs can be stored. This isn't a new concept, and it harkens back to early implementations of LeftHand -- before HP, now Hewlett Packard Enterprise, acquired it. The VSAN architecture is sophisticated; it has elastic scaling, quality-of-service features, cache-based acceleration, VM-aware policy control and many other features.
VSAN is best suited for IT shops that want a scale-out, self-contained architecture, but VSAN isn't the only option from the vast VDI storage market.
Citrix acquired Sanbolic in January 2015. Sanbolic provides a similar product to VSAN, as does a company called DataCore. In fact, companies can deploy the DataCore product, SANsymphony, with as few as two nodes, and it supports all major hypervisors.
Further out on the fringe are storage acceleration vendors that help companies get more value from the storage they already own. These products work in a variety of ways. Some place a shim in the operating system inline to the existing I/O stream and optimize against flash or RAM. Other products are virtual appliances that IT administrators can assign storage to; they front end that storage back to the host they live on as a network file system (NFS) volume. Still others use agents inside the OS to sequence what would otherwise be random write processes.
PernixData Inc. and Infinio Systems Inc. both fall into the acceleration bucket. Both products take the approach of placing a shim or using VMware's vSphere Storage APIs Array Integration framework for I/O filtering to accelerate with either an in-host solid-state drive, allocated host memory or a combination of both.
A back-to-school quiz on VDI storage and backup
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Although these products seem familiar, the details are important. Pernix's FVP product began by accelerating NFS whereas early implementations of Infinio seemed limited to block storage. Both products run well. The Pernix interface is more user-friendly and intuitive, but Infinio's reporting and visibility is slightly ahead of Pernix's. Of course the pros and cons change with each product release.
Condusiv Technologies Corp. is another vendor to watch out for in the software-only VDI storage market. Condusiv's V-locity product is typically installed on the VM's guest operating system as an I/O filter driver and is usually for high-performance database servers and I/O-intensive workloads.
But there is an interesting use case for VDI: Admins could sequence and write the small, randomized read-write profile of a desktop VM to contiguous blocks of storage in a single operation. This look-ahead write sets up a faster read process down the road. The product then couples with a predictive algorithm that preloads anticipated reads into DRAM, which reduces the load time dramatically. These two processes together could be especially useful for performance-oriented VDI applications.