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Comparing Nasuni and EMC Isilon

Is Nasuni an Isilon Competitor? When I talk to IT organizations about scalable NAS, I find many either own or are considering Dell EMC Isilon. Since Nasuni provides a unified set of enterprise file services that encompass scalable NAS, the question of Dell EMC Isilon vs. Nasuni often comes up.

Nasuni’s marketing people will say Nasuni is the next-generation platform, with the first cloud-native file system that provides greater scalability than any other solution and the fastest-growing customer base.

Dell EMC’s marketing people will say Isilon is the #1 scale-out NAS platform with the largest installed base and a leader position in the Gartner Magic Quadrant for Distributed File Systems and Object Storage.

I’m going to try to cut through the marketing FUD. Although these two solutions ostensibly have the same goal, the ways they deal with unstructured data storage growth are radically different. Here’s my take on what the technical differences are, why they matter, and what I’m hearing from the customers I talk to every day as a storage solutions engineer.

By the end, you’ll hopefully have a richer understanding of both products and the ideal use cases for each.

Scalable NAS Architecture Basics

Let’s start with a basic overview of each solution’s approach to scalable NAS.

EMC Isilon

EMC Isilon was designed to provide traditional on-premises Network Attached Storage (NAS), but in a way that overcomes some of the scalability and flexibility limitations inherent in competitive products. Isilon does this by building a clustered system of compute, networking and storage building blocks, much like hyperconverged systems. Except that in Isilon’s case, the building blocks, or nodes, are dedicated to storage rather than hosting virtual machines.

The nodes are connected to each other in clusters on the back end through an InfiniBand connection. Traditional Ethernet connections and NAS protocols connect EMC Isilon clusters to clients and management interfaces on the front end. Different node types provide differing levels of connectivity depending on their mission – capacity-oriented or performance-oriented. Data is striped across nodes, and active blocks or metadata in nodes are tiered into flash for high-performance access.

IT manages the system through a web-based or command line interface for each cluster.


Nasuni is designed to leverage cloud object storage. Nasuni’s architects believe cloud storage is the “new disk,” and offers greater scalability, durability, and geo-redundancy (and cost savings) than any on-premises NAS architecture ever could. Nasuni’s “cloud-first” architecture puts the gold copy of all data in cloud object storage, and uses edge appliances to locally cache the active data on-prem.

Like Isilon, clients read from and write to the edge appliance cache using standard Ethernet connections and protocols. Unlike Isilon, all file changes are sent to the cloud object storage volume continuously, with versions kept indefinitely (or for a shorter time if policy requires). Many edge appliances in different locations or in the same location can connect to the same object store and share the same data volume in the cloud.

IT manages the system through a single pane of glass web interface that talks to each of the edge appliances via cloud message queuing.

Nasuni Whiteboard

Now that you have a basic understanding of the architectures, I’ll try to do an apples-to-apples feature comparison and explain why the differences matter.

File Systems – Dell EMC OneFS vs. Nasuni UniFS®

Both companies agree scalable NAS starts with a scalable file system. Where they disagree is how it should work.

Dell EMC Isilon OneFS uses physical pointers and extents for metadata and stores file and directory metadata in inodes on disk. OneFS coordinates the distribution of this information across the Isilon cluster. There is a limit to a cluster of 68 PB. By striping data across systems in the cluster, OneFS also provides cross-node redundancy to allow an Isilon cluster to survive the failure of any one node (or more, depending on the configuration.)

Nasuni UniFS is the first cloud-native file system, storing file and metadata in inodes that “live” in cloud object stores. UniFS offers unlimited volume size in the cloud, and enables many edge appliances to access the same volume of data on-premises. This hybrid cloud architecture means UniFS inherits the scalability, durability and geo-redundancy of the cloud object store, while the edge appliances leverage the local security and high-performance access of traditional on-premises NAS devices.

Why It Matters

Nasuni UniFS allows for unlimited scaling of data in the cloud. Active data is cached locally in stateless edge appliances. While each appliance has access to the unlimited pool of data in the cloud, only a small fraction of the data is active and stored locally. In effect, UniFS is decoupling the size of the file system, or the total body of files and metadata, from the local hardware. As one Nasuni customer says, “It’s like stuffing 20 pounds of potatoes into a 5-pound bag.”

This provides an extremely functional, flexible, and cost-effective model for most unstructured data workloads, including group shares and home directories that need to store Office files, CAD/CAM, Adobe creative content, medical images, video, and more. Appliances are available in a range of sizes, from desktop towers for small offices to all-flash systems for high performance access at large corporate locations.

With EMC Isilon, all data that could possibly be accessed must live in the on-prem cluster. As data grows, more hardware modules must be added. This is a solid model for file workloads that require extremely high IOPS and throughput. Isilon also offers different node types that can focus more on capacity to reduce costs in cases where high IOPS isn’t a requirement. But even these lower cost nodes still require additional local hardware. Smart pools allow policy-based tiering to different node types, while Cloud pools allow policy-based tiering to object storage with stubbing of files, but these features are only suitable for truly cold data – the files you will almost certainly never need to access.

Bottom line: Nasuni UniFS offers greater scalability at lower cost for general purpose file workloads than Isilon OneFS. The intelligent caching algorithms of UniFS ensure the files users need are almost always available locally with much less on-prem hardware, striking an optimal balance between capacity, performance and cost. The OneFS approach of requiring all data to be stored locally in on-prem arrays is suited for specialty, high-IOPS workloads. Anything beyond that will require tiering between pools, which forces administrators to decide how and when data should move, and what volumes can live on local hardware vs. what can live in the cloud.

Data Protection – Nasuni Continuous File Versioning vs. EMC Isilon Snapshot and 3rd Party Backup

When you have large-scale NAS storing petabytes of files, you need a seamless way to protect those files. Again, Nasuni and Dell EMC Isilon both check the boxes, but in very different ways.

With Nasuni, data protection is built into UniFS, and is another byproduct of the cloud-native file system. Using a new data protection approach called continuous file versioning, Nasuni sends data to the cloud as changes are made. This enables an unlimited version history of every file to be kept in the cloud object store for little extra cost, since only the deltas are sent. Compression and deduplication make each version even more space-efficient. This approach enables any previous version of any file to be restored from the cloud in minutes, for significantly improved Recovery Point and Recovery Time objectives (RPOs and RTOs).

With EMC Isilon, you have a few different choices. Isilon OneFS utilizes a snapshot capability called SnapShotIQ that enables up to 1,024 snapshots to be configured at different levels in the file system tree. This configuration provides flexibility, but snapshots are written locally, which means they consume costly local storage and only address local backup.

For off-site backup using this SnapShotIQ, the entire data set and snapshot history must be replicated to a second, similarly sized Isilon cluster located at another site. While some customers adopt this approach, others find the cost of maintaining duplicate Isilon infrastructure too high, and opt for traditional backup instead.

However, traditional backup and disaster recovery solutions also incur significant software, hardware and IT administration costs, and often fail to meet the RPOs and RTOs needed by the business.

Why It Matters

Nasuni customers never deal with the cost, management or reliability issues of separate data protection solutions or the capacity constraints imposed by local snapshots. Instead, data protection just happens. Unstructured data is continuously and automatically stored off-site in secure, redundant storage, ready for restore at any time. Recovering deleted files or restoring the last version of a file before it was infected by Ransomware or malware is fast, easy, and affordable. As one Nasuni customer says “With the ability to recover a file or directory up to the minute, we no longer need to worry about a Ransomware attack causing a major loss of productivity.”

Isilon customers are forced into a trade-off. They either incur the heavy cost of duplicate Isilon infrastructure to support local and/or off-site snapshots. Or, they use slightly less costly third party backup solutions and accept that the RPOs and RTOs may not support the needs of the business.

Disaster Recovery – Nasuni Stateless Edge Appliances vs. EMC Isilon Cluster Replication

Disaster recovery (DR) is the next key requirement of scalable NAS.

For Nasuni, DR is another built-in capability of its cloud-native architecture. If a Nasuni Edge Appliance fails or a location is destroyed, a new Edge Appliance can be instantiated and pointed to the cloud object store anywhere there is power and connectivity. The Edge Appliances are essentially stateless, since the authoritative copies of all files and metadata are stored in the cloud object store. As a result, the appliances only need to be as big as the active data to provide full DR capabilities, with only Internet bandwidth required to populate them.

Customers can have a new virtual or physical Edge Appliance, identically configured to the one that was lost, up and running in 15 minutes. Stand-by Edge Appliances can also be kept running and populated for warm fail-over in preparation for a DR event.

For Isilon, solving for DR is like solving for backup. Entire clusters must be replicated to an off-site DR location. This means a duplicate Isilon infrastructure at the DR site along with the associated inter-site communications costs – usually MPLS bandwidth – must be purchased at significant cost to the business. As the NAS environment grows, so, too, will DR costs.

Why It Matters

Access to critical file data must be maintained in the event of a disaster. Traditional backup does not provide DR capabilities, as it generally takes too long to restore an entire data set from a backup. This means a separate DR capability for file storage is required.

“If we lost our data center, all we would have to do is find a PC, install a viewer, and point to the Nasuni share in the cloud, it would literally take minutes to recover data.”

-Paul Feilmeier, Faith Regional Health Services

Nasuni provides built-in DR without requiring the extra cost and management overhead of a duplicate infrastructure. With Nasuni, file access through a virtual or physical appliance Edge Appliance can be quickly restored anywhere that connectivity to the cloud object store is available. Paul Feilmeier, IT Infrastructure Manager at Faith Regional Health Services explains, “If we lost our data center, all we would have to do is find a PC, install a viewer, and point to the Nasuni share in the cloud,” Feilmeier explains. “It would literally take minutes to recover data.”

Isilon DR will require more than double the cost of the primary NAS environment, since a duplicate EMC Isilon cluster and MPLS bandwidth to that cluster is required.

Multiple Site Access – Nasuni Local Edge Appliances vs. EMC Isilon Remote Access or Replication

Many enterprises that choose a scalable NAS solution have multiple offices and remote branches that require access to the same files.

Nasuni provides access to unstructured data across all locations and mobile devices as part of its cloud-first architecture. Nasuni Edge appliances can be placed at any location to provide access to the same gold copies of files stored in the cloud. Intelligent caching provides fast local access to active files at each site.

Isilon stores its data in local drives. A user in one location who attempts to access data at a different office must do so through add-on solutions – typically VPNs, replication, or WAN optimization/acceleration.

Remote users trying to access data over a VPN often hit major latency problems. WAN optimization can help with this, but sometimes exacerbates latency issues by adding another ‘bump in the wire.’ If projects require the opening and accessing of many files, the round-trip latency can add up and delay access to project data.

EMC Isilon customers can use replication as a way to offer multi-site access, but, as with DR and backup, this requires duplicate infrastructure, which increases costs and creates editing conflicts. As users in multiple locations work on the same files, there is no single source of truth.

Why It Matters

Most enterprises that require scalable NAS do not have users in one central location. Files must be accessed from many locations and efficiently managed across sites.

Nasuni’s cloud-native architecture provides fast, cached access to the authoritative source of files stored in the cloud from any location. This approach enables users to be productive, while maintaining file integrity and minimizing IT costs.

Isilon’s traditional, drive-centric architecture means that multi-site access will require costly remote solutions that are susceptible to latency issues, or very expensive replication solutions that will result in multiple gold copies of the same file.

Collaboration Across Sites – Nasuni Global Lock and Change Propagation vs. EMC Isilon Local Lock and Cluster Replication

In addition to accessing data across sites, there is often a need for enterprises to support collaboration across sites, allowing multiple users to edit the same file, whether they are simple office documents or complex engineering project files.

Nasuni’s cloud-native architecture provides a global namespace that is inherently designed for multi-site access and collaboration. Every user is essentially accessing the same file in the cloud, even though the file is really cached locally on an Edge Appliance. Nasuni augments this with cloud-based global locking, which prevents any conflicts between users editing the same files from different locations.

There is a small amount of latency added to acquire a lock from the global lock server in the cloud. Changed data must then propagate through the cloud to each Edge Appliance where it is needed. Nasuni’s method of chunking, deduplicating and compressing the data means only the changed portion of data moves. This limits bandwidth usage and optimizes the entire process, resulting in consistently minimal latency across all locations. The combination of global locking and sharing the gold copy of files in the cloud through cached local copies supports global project collaboration, while still providing fast file access for users.

Isilon is a single-site, drive-centric solution, with the gold copies of files stored locally. As a result, remote access (VPN, WAN optimization) or replication technologies must be used for multi-site collaboration.

If file data is confined to a single location, local locking will prevent file conflicts, and latency will be almost negligible. However, the latency across the WAN can make even remote access, as discussed above, slow and difficult, let alone collaboration. If access times are acceptable, there is no added latency in acquiring locks, nor are there delays in moving file data to different caches.

If replication is required to make files local to users and reduce access times, collaboration may be impossible. Replicated Isilon environments will have different copies of the same files. Users working on them at the same time can create conflicts. Without any central source of truth or global lock, data loss may result. As with DR and backup, maintaining replicated Isilon clusters at multiple locations also translates into added CapEx and OpEx.

Why It Matters

Collaboration on projects across sites has become a business imperative in this age of global growth. Users with different skills or different resources are often found in different locations. When those skills can be brought to bear on a shared project, an enterprise instantly becomes more agile, responsive and efficient. For this to work, though, the files that support these projects and applications must be available to all users with minimum delay and full coherence.

Nasuni is built for regional and global collaboration. A single gold copy of each project file is stored in the cloud and cached locally in Edge Appliances for fast access. For one Nasuni customer, collaboration across their 4 U.K. offices is a key requirement for design teams working on high profile projects across the world. “We’re changing the way the company thinks about how we can really drive the efficiency in our business and make us much more agile.”

Users in different regions can access the most recent version of project files, and global locking prevents editing conflicts. All of this is done without the additional costs and inefficiencies of traditional drive-centric, single-site architectures like Isilon.

Mobility – Nasuni Mobile vs. EMC Isilon Third Party Products

To support remote office/branch office and work-from-home initiatives, mobility is a strategic focus for many enterprises. Mobile access to files is an important part of this.

The Nasuni platform includes Nasuni Mobile, which offers file access through iOS and Android applications as well as a Web browser option and a sync application for Windows and Mac environments. Mobile access to files happens through Edge Appliances, which means Active Directory and the Nasuni security model, in which the customer holds the encryption key, both apply. Mobile access is managed through the same single pane of glass management console that manages Edge Appliances.

“Access to files on mobile devices and collaboration between users is a critical requirement for the modern, on-the-go worker.”

Isilon does not provide mobile access as part of its platform. To provide mobile access to files in an Isilon environment, IT organizations must deploy third party products or separate cloud services. Third party products can be used to access the data directly from the Isilon cluster and provide access to mobile devices. Alternatively, cloud file sync and share products can be used, but these create a separate store that makes policy and security more difficult to administer, and creates new islands of file data.

Why It Matters

Access to files on mobile devices and collaboration between users is a critical requirement for the modern, on-the-go worker. Only Nasuni offers an integrated mobile solution that reduces total cost of ownership and management overhead, provides integrated security and delivers mobile access to files anytime, through any device.

Management – Nasuni Distributed Management vs. EMC Isilon Single Instance Management

The last key requirement of scalable NAS is the ability to manage a large-scale deployment.

Nasuni includes the Nasuni Management Console (NMC), a single pane of glass solution that manages all functions across a distributed implementation, including the management of volumes, shares, Edge Appliances, data protection policies, version restore and DR configurations, Nasuni Mobile settings and more. Remote Edge Appliances in any location are managed via cloud messaging and do not require a direct connection to the device. The entire Nasuni platform can be deployed and managed from a single interface, with role-based access control available to separate functions for large IT teams.

Isilon also offers a web-based interface to provide a single point of management for an entire cluster. However, this is designed for Isilon’s single-volume, single-name space architecture. If you deploy a second Isilon cluster for data protection, DR, or multi-site access as discussed above, that will require a separate management console and a second point of management. If you avoid replicating Isilon clusters to maintain a single, local source of files, then separate third party backup, DR, WAN optimization and mobile access products may all be required – all of which, in turn, require their own separate management consoles.

Why It Matters

IT management is increasingly complex. A solution that combines storage, data protection, DR, multi-site access and mobile access into a single platform with a single point of management will be significantly easier to manage than a solution that requires a new point of management for every replicated cluster or 3-5 separate third party tools for each add-on function.

By offering an integrated set of cloud-scale enterprise file services, Nasuni (short for NAS Unified) simplifies large-scale NAS deployments, minimizes the risk of administrative errors and product incompatibilities, increases IT agility and reduces costs.

“A solution that combines storage, data protection, DR, multi-site access and mobile access into a single platform with a single point of management will be significantly easier to manage…”

The Bottom Line

Nasuni and Dell EMC Isilon both offer powerful file services solutions to enterprises that are dealing with the massive growth of unstructured data. Which solution you should use comes down to what’s best suited for your environment.

Nasuni is a good choice if you need to:

  • Scale NAS capacity on-demand to hundreds of TBs or PBs without making major investments in on-premises drives;
  • Offer improved recovery points and recovery times to meet business needs and mitigate Ransomware and malware, without the cost of duplicate NAS infrastructure;
  • Provide for disaster recovery without the cost and complexity of duplicate NAS infrastructure, DR sites, and MPLS connectivity;
  • Support file access and collaboration from multiple locations without costly WAN acceleration or replication, and without creating duplicate gold copies of files;
  • Offer secure mobile file access from any device in support of mobility initiatives without third party tools or file sync and share silos;
  • Manage multiple locations through a single pane of glass console;
  • Leverage a preferred cloud object store and support “cloud-first” business initiatives

Dell EMC Isilon is a good choice if you need to:

  • Prioritize NAS performance over capacity for IO-intensive file workloads;
  • Support only TB-scale file storage needs;
  • Provide basic RPOs and RTOs using traditional backup tools, or you have a small enough NAS environment to afford off-site snapshots;
  • Provide basic DR, or if your NAS environment is small enough that you can incur the cost of replicated NAS infrastructure, DR sites, and MPLS connectivity;
  • Support file access and collaboration for only a few locations;
  • Limit mobile file access, or if you have already invested in separate file sync and share products;
  • Manage clusters for only a few locations and a single name space;
  • Delay your move to the cloud, and would rather learn from others who are deploying cloud-first solutions.

This is my take. If you have other thoughts, I’d be happy to hear from you. Comment below or email me at warnold (at) nasuni (dot) com.