I was intrigued to read that NAS (Network-Attached Storage) virtualiser Attune was partnering NetApp. After all NetApp can virtualise its own NAS and other vendors' drive arrays too. Why did it need Attune?

I asked Attune spokesperson Daniel Liddle, VP of marketing, 'How does Attune's Maestro File Manager compare and contrast with Data ONTAP 7G, GX, and with NetApp's V-filer?'

This is what he said.

NetApp products are completely complementary to Attune’s Maestro file manager solution. NetApp does not offer a heterogeneous NAS virtualisation solution and has elected to partner with us in this area.

The ONTAP operating systems efficiently runs their hardware and is what exposes NFS exports and CIFS shares. Their virtualisation capabilities from the Spinnaker acquisition may sound somewhat similar but are focused on creating a single, larger virtual NAS entity by clustering identical high performance, homogeneous hardware. We would interface this larger, faster NAS device in exactly the same way we do their other tier 1 and tier 2 devices.

Our Network File Management (NFM) a.k.a. NAS Virtualisation solution is designed to reduce the operating costs and simplify the management of heterogeneous enterprise file serving resources and NAS devices.

We create a global namespace over muti-vendor equipment and across multiple generations of systems. We also provide non-disruptive migration, capacity expansion, server retirement and file-level tiering between different classes of NAS and file server resources.

In a pure NetApp environment, a good example would be creating automated tiering between high-end 7G systems and their tier-2 R200 devices. A system administrator could set a policy that transparently (and non-disruptively) identifies and moves all of the stale files (infrequently accessed) off of their high performance and more expensive servers onto their lower cost (but adequate performance) R200 devices.

This optimises their existing resources by automatically aligning the changing data requirements with the appropriate tier of underlying storage. This tiering happens in the background, yet the clients would still see their data in the original location, even if system administrator or tiering policy physically moved the file to a new location. There are numerous other unique value-added capabilities that we provide to pure NetApp and mixed environments, as well.

Okay, that makes sense. The Attune announcement mentioned that its product had truly native CIFS support which gave it an advantage over other NFM suppliers who only offer native NFS and non-native CIFS. I asked Liddle, 'What are the practical significant Windows advantages and practical advantages of 'truly native CIFS support'? His reply follows.

All NAS virtualisation devices operate at the file level (not at the block level) and interact with file servers and NAS devices using CIFS and NFS protocols. They must look like a server to the clients and like a client to the servers. NFS is a well documented and understood protocol that is fairly straightforward to “virtualise.” However, CIFS is another story.

CIFS is a robust protocol that is entirely controlled by Microsoft and is not considered “open” or documented in the same fashion for third-parties. As a result, Linux-based NAS virtualisation vendors must, in effect, reverse-engineer the protocol without complete or comprehensive documentation. As a result again, they can face major challenges just getting simple elements and capabilities to behave properly — and future changes to the protocol could create significant issues.

While there is an open source project (Samba) that is dedicated for that cause to provide CIFS functionality for Linux, it is exactly that – an effort by the open community to reverse engineer CIFS constructs and share that knowledge. Therefore, any non-Windows implementation of CIFS typically is missing some key attributes and only deliver basic functionality.

In fact, it is interesting to note that even NetApp explicitly acknowledges it does not deliver full CIFS functionality in its Data ONTAP GX Technical Specifications: Network Protocol Support - NFS V2/V3 over UDP or TCP, Microsoft CIFS (basic functionality only).

Some of the common difficulties and limitations around implementing truly native CIFS include full support for security/privilege attributes for files or shares, highest level of authentication (i.e. security) support, proper full implementation for oplocks for optimal performance, etc. For a good quick overview of some of the difficulties of implementing CIFS on a non-Windows platform, refer to the introduction of the book 'Implementing CIFS'.

Attune is the only independent NAS virtualisation solution that is based upon a Windows platform. One of the primary benefits of this is this truly native support for the protocol and all of the work (and interoperability testing) that Microsoft does. Having support agreements for rapid bug resolution and visibility into current and future Windows (CIFS) functionality is a major advantage to a vendor such as us.

Thirdly, I asked if Attune 'could provide a 'compare and contrast statement' about Maestro File Manager and Acopia and NeoPath?

Acopia provides a specialised hardware platform that is dependent upon custom ASICs as the foundation of their NFM functionality. While it delivers key NFM functions such as global namespace, heterogeneous file resource pooling, and automated tiering functionality as Attune does, there are some differences.

Acopia does not provide a gradual deployment approach. The user has to choose whether specific storage resources are going to be managed by Acopia or leave it independent. All traffic wishing to access data on a particular server that the Acopia device is managing must be routed through that device—typically also by reconfiguring VLANs.

The same data and servers cannot be accessed directly (normally) by regular users and simultaneously through the device by a subset of users (or system administrators) trying it out. This can be perceived by system administrators as a very risky cut-over deployment model.

By contrast, Attune has three concurrent operational stages providing the most gradual and low-risk deployment of any NFM device. Our first stage is actually out of band Discovery Mode which shows the system administrator all of their storage resources on the network and allows them to look at track and report on not only file usage information but also specific server performance (latency, throughput, capacity, et cetera) without ever passing any client data through our device.

The second concurrent stage is called Native Mode. This mode also leaves the file data in its original location and format, yet allows them to see some more of the benefits including global namespace. We have a unique capability called Dual Path Access™ that allows concurrent/simultaneous access by clients both directly to the server (as normal) or through the Maestro File Manager (MFM).

The third stage is Extended Mode and this includes a number of critical customer-requested capabilities that Acopia does not.

The MFM is also implemented on standard off-the-shelf hardware, thus enabling quick transition to new platforms as technology improves. Other key capabilities not supported by Acopia (or NeoPath) include powerful functionality such as Dynamic Volume Expansion, Small File Acceleration and Adaptable Striping and Mirroring. Finally, Attune delivers truly native CIFS support (leveraging Windows OS), while Acopia delivers re-engineered CIFS through a non-Windows platform.

NeoPath also provides an NFM solution based on standard off-the-shelf hardware and delivers NFM functions such as global namespace, heterogeneous server support, and file-level tiering functionality — but that is where the similarities end. They support even fewer of the important capabilities (mentioned above) than Acopia. They also have developed their solution upon a non-Windows platform and have the same sort of re-engineering challenges.

In short, Attune has come out with a unique and powerful set of new NFM capabilities which are complemented by the lowest-risk, most gradual deployment model of these vendors. The deployment model considerations are particularly important to reducing the sales cycle and increasing system administrator’s comfort in adopting a new technology for virtualising their backend file servers and NAS devices.