An Introduction to Unity: EMC’s New Midrange Storage System

Fresh off of its launch at EMC World, I’d like to share a quick introduction to the new EMC storage system: EMC Unity. For the purposes of this write-up, I’ll be focusing on the overall Unity architecture vs. model numbers and spec sheets, which should be readily available from EMC.

What is it?

Unity is EMC’s new midrange storage product line that effectively replaces the VNX2 family. It will be available in all-flash and hybrid versions. The system has been streamlined in many significant ways with an emphasis on simplicity and efficiency. Here are some of the product highlights as I see them:

Truly Unified

VNX2 introduced a more granular pool design (256MB slices) with the ability to do redirect-on-write snapshots at 8KB granularity. However, this enhancement was made to the block components of the system and had little benefit to the physically separate file components that had their own snapshot mechanism. This is a challenge with any physical file gateway approach, i.e. it is more difficult to make mutually beneficial enhancements when block and file run on different components with different code bases.

With Unity, there are no separate file gateways as there were in the past (say goodbye to X-Blades and Data Movers). The file code has been updated and redesigned to run on the two Storage Processors (SPs) that previously handled only block workload. Furthermore, block, file, and VVols all leverage the common pool design introduced in VNX2.


  • The controller components of a VNX 5800 took up a minimum of 7U in a rack. By eliminating the need for X-Blades and streamlining the hardware design, a Unity 600F (largest model) takes up only 2U.
  • There is now one redirect-on-write snapshot mechanism for all storage protocols, independent of file or block use case.
  • The previously file-exclusive Replicator product now leverages the common snapshot mechanism to track deltas and can be used for both file and block. Note that a RecoverPoint write splitter is also supported as with prior VNX systems.

File Updates

The file capabilities of prior generation VNX systems were in need of updating (16TB filesystem limit, COFW snaps/SavVol management, etc.). Leveraging the opportunity created through integrating the file and block code, EMC made several notable file improvements:

  • “NAS Servers” are a virtual entity for multi-tenancy, each with its own network interfaces, protocols, security, etc.
  • Maximum filesystem size is now 64TB
  • Auto-shrink/extend for filesystems
  • Storage reclamation (automatic or user initiated)
  • Up to 256 VMDK clones
  • Continued broad protocol support, including SMB 3.02
  • 64-bit code

Notes on Space Efficiency

Space efficiency in storage systems is an evolving balance of engineering complexity vs. market dynamics. From an engineering perspective, a capability such as inline deduplication is extraordinarily difficult to add to a system that wasn’t designed for it in the first place. From a market perspective, flash continues to get more dense and less expensive (and less reliable, but that’s another topic).

When EMC introduced SLC flash in the DMX4 in 2008 at around $80K per terabyte, the need to pull out all the stops to efficiently use flash capacity at that price point led to the wave of startups that brought inline deduplication and/or compression to primary storage. As always happens with technology, today’s much lower price points can allow for simpler design decisions.

With these market dynamics in mind, Unity no longer supports the 8KB post-process block deduplication and file single-instancing of the VNX2. Beyond thin provisioning, space-efficient snaps, and VMDK cloning, inline compression is forecasted by EMC to arrive in Unity by the end of the year.

Other Notables

  • The management interface is now (finally!) HTML5. No more Java insanity.
  • Management tasks are greatly simplified by the improvements described above. Tasks can be handled by GUI, CLI or REST API.
  • Unity Virtual Storage Appliance (VSA) is a virtual version of Unity that comes in a free Community Edition and a subscription-licensed Professional Edition. Note that there are some feature limitations of VSA vs. a physical Unity system.
  • FAST Cache now offers online expansion and reduction.
  • Controller-based encryption remains, eliminating the need to use SEDs.
  • At launch, flash drive options include 1.6TB and 3.2TB eMLC drives. Expect the introduction of cheaper, less-reliable media over time as inline compression and other physical flash management features are introduced.
  • The back end is now 12Gb SAS.

Why is This Important?

With literally hundreds of thousands of CLARiiON and VNX systems sold over the past 25 years, EMC’s midrange storage line holds a substantial presence in the market. The enhancements described herein gives Unity a competitive price/performance balance (entry all-flash version starting under $18K), easier management, and a true unified feature set.

Competitive Landscape

Unity comes into the midrange storage market with more competition than ever, ranging from long-tenured players like NetApp, HPE 3PAR, and the lower end of the HDS VSP G/HNAS lines to newer hyperconverged/software-defined and flash players such as Tintri, Nimble Storage, Nutanix, and Pure Storage. The improved file capability is notable as many of these systems are block or for virtualization platforms only.

If you’re interested in learning more about EMC Unity, feel free to reach out to me directly via email at or Twitter @ScottReder. Or, schedule a time to meet one-on-one with the AHEAD team in the Lab and Briefing Center.

AHEAD Lab and Briefing Center