Clustered File Systems: No Limits

Today’s storage world would appear to have been divided into three major and mutually exclusive categories: block, file and object storage. The marketing that shapes much of the user demand would appear to suggest that these are three quite distinct animals, and many systems are sold as exclusively either SAN for block, NAS for file or object. And object is often conflated with cloud, a consumption model that can in reality be block, file or object.

A fixed taxonomy that divides the storage world this way is very limiting, and can be confusing; for instance, when we talk about cloud. How should providers and users buy and consume their storage? Are there other classifications that might help in providing storage solutions to meet specific or more general application needs? What about customers who need file access performance beyond what one storage box can provide? Which options support those who want scale-out solution like object storage with file protocol semantics?

To clear up the confusion, the SNIA Ethernet Storage Forum is hosting a live Webcast, “Clustered File Systems: No Limits.” In this Webcast we will explore clustered storage solutions that not only provide multiple end users access to shared storage over a network, but allow the storage itself to be distributed and managed over multiple discrete storage systems. You’ll hear:

  • General principles and specific clustered and distributed systems and the facilities they provide built on the underlying storage
  • Better known file systems like NFS, IBM Spectrum Scale (GPFS) and Lustre, along with a few of the less well known
  • How object based systems like S3 have blurred the lines between them and traditional file based solutions

This Webcast should appeal to those interested in exploring some of the different ways of accessing & managing storage, and how that might affect how storage systems are provisioned and consumed. POSIX and other acronyms may be mentioned, but no rocket science beyond a general understanding of the principles of storage will be assumed. Contains no nuts and is suitable for vegans!

As always, our experts will be on hand to answer your questions on the spot. Register now for this October 25th event.

Update: If you missed the live event, it’s now available  on-demand. You can also  download the webcast slides.

NFS FAQ – Test Your Knowledge

How would you rate your NFS knowledge? That’s the question Alex McDonald and I asked our audience at our recent live Webcast, “What is NFS?.” From those who considered themselves to be an NFS expert to those who thought NFS was a bit of a mystery, we got some great questions. As promised, here are answers to all of them. If you think of additional questions, please comment in this blog and we’ll get back to you as soon as we can.

Q. I hope you touch on dNFS in your presentation

A. Oracle Direct NFS (dNFS) is a client built into Oracle’s database system that Oracle claims provides faster and more scalable access to NFS servers. As it’s proprietary, SNIA doesn’t really have much to say about it; we’re vendor neutral, and it’s not the only proprietary NFS client out there. But you can read more here if you wish at the Oracle site.

Q. Will you be talking about pNFS?

A. We did a series of NFS presentations that covered pNFS a little while ago. You can find them here.

Q. What is the difference between SMB vs. CIFS? And what is SAMBA? Is it a type of SMB protocol?

A. It’s best explained in this tutorial that covers SMB. Samba is the open source implementation of SMB for Linux. Information on Samba can be found here.

Q. Will you touch upon how file permissions are maintained when users come from an SMB or a non-SMB connection? What are best practices?

A. Although NFS and SMB share some common terminology for security (ACLs or Access Control Lists) the implementations are different. The ACL security model in SMB is richer than the NFS file security model. I touched on some of those differences during the Webcast, but my advice is; don’t expect the two security domains of SMB (or Samba, the open source equivalent) and NFS to perfectly overlap. Where possible, try to avoid the requirement, but if you do need the ability to file share, talk to your NFS server supplier. A Google search on “nfs smb mixed mode” will also bring up tips and best practices.

Q. How do you tune and benchmark NFSv4?

A. That’s a topic in its own right! This paper gives an overview and how-to of benchmarking NFS; but it doesn’t explain what you might do to tune the system. It’s too difficult to give generic advice here, except to say that vendors should be relied on to provide their experience. If it’s a commercial solution, they will have lots of experience based on a wide variety of use cases and workloads.

Q. Is using NFS to provide block storage a common use case?

A. No, it’s still fairly unusual. The most common use case is for files in directories. Object and block support are relatively new, and there are more NFS “personalities” being developed, see our ESF Webcast on NFSv4.2 for more information.  

Q. Can you comment about file locking issues over NFS?

A. Locking is needed by NFS to maintain file consistency in the face of multiple readers and writers. Locking in NVSv3 was difficult to manage; if a server failed or clients went AWOL, then the lock manager would be left with potentially thousands of stale locks. They often required manual purging. NFSv4 simplifies that by being a stateful protocol, and by integrating the lock management functions and employing timeouts and state, it can manage client and server recovery much more gracefully. Locks are, in the main, automatically released or refreshed after a failure.

 Q.  Where do things like AFS come into play? Above NFS? Below NFS? Something completely different?

A. AFS is another distributed file system, but it is not POSIX compliant. It influenced but is not directly related to NFS. Its use is relatively small; SMB and NFS dominate. Wikipedia has a good overview.

Q. As you said NFSv4 can hide some of the directories when exporting to clients. Can this operation hide different folders for different clients?

A. Yes. It’s possible to maintain completely different exports to expose or hide whatever directories on the server you wish. The pseudo file system is built separately for each server export. So you can have export X with subdirectories A B and C; or export Y with subdirectories B and C only.

Q. Similar to DFS-N and DFS-R in combination, if a user moves to a different location, does NFS have a similar methodology?

A. I’m not sure what DFS-N and DFS-R do in terms of location transparency. NFS can be set up such that if you can contact a particular server, and if you have the correct permissions, you should be able to see the same exports regardless of where the client is running.

Q. Which daemons should be running on server side and client side for accessing filesystem over NFS?

A. This is NFS server and client specific. You need to look at the documentation that comes with each.

Q. Regarding VMware 6.0. Why use NFS over FC?

A. Good question but you’ll need to speak to VMware to get that question answered. It depends on the application, your infrastructure, your costs, and the workload.

Update: If you missed the live event, it’s now available  on-demand. You can also  download the webcast slides.

Next Live Webcast: NFS 101

Need a primer on NFS? On March 23, 2016, The Ethernet Storage Forum (ESF) will present a live Webcast “What is NFS? An NFS Primer.” The popular and ubiquitous Network File System (NFS) is a standard protocol that allows applications to store and manage data on a remote computer or server. NFS provides two services; a network part that connects users or clients to a remote system or server; and a file-based view of the data. Together these provide a seamless environment that masks the differences between local files and remote files.

At this Webcast, Alex McDonald, SNIA ESF Vice Chair, will provide an introduction and overview presentation to NFS. Geared for technologists and tech managers interested in understanding:

  • NFS history and development
  • The facilities and services NFS provides
  • Why NFS rose in popularity to dominate file based services
  • Why NFS continues to be important in the cloud

As always, the Webcast will be live and Alex and I will be on hand to answer your questions. Register today. Alex and I look forward to hearing from you on March 23rd.

Update: If you missed the live event, it’s now available  on-demand. You can also  download the webcast slides.

New White Paper: An Updated Overview of NFSv4

Maybe you’ve asked yourself recently; “Hmm, I wonder what’s new in NFSv4?” Maybe (and more likely) you haven’t; but you should.

During the last few years, NFSv4 has become the version of choice for many users, and there are lots of great reasons for making the transition from NFSv3 to NFSv4. Not the least of which is that it’s a relatively straightforward transition.

But there’s more; NFSv4 offers features unavailable in NFSv3. Parallelization, better security, WAN awareness and many other features make it suitable as a file protocol for the next generation of applications. As a proof point, lately we’ve seen new clients of NFSv4 servers beyond the standard Linux client, including support in VMware’s vSphere for virtual machine datastores accessible via NFSv4.

In this updated white paper, An Updated Overview of NFSv4, we explain how NFSv4 is better suited to a wide range of datacenter and high performance compute (HPC) uses than its predecessor NFSv3, as well as providing resources for migrating from v3 to v4.

You’ll learn:

  • How NFSv4 overcomes statelessness issues associated with NFSv3
  • Advantages and features of NFSv4.1 & NFSv4.2
  • What parallel NFS (pNFS) and layouts do
  • How NFSv4 supports performant WAN access

We believe this document makes the argument that users should, at the very least, be evaluating and deploying NFSv4 for use in new projects; and ideally, should be using it wholesale in their existing environments. The information in this white paper  is meant to be comprehensive and educational and we hope you find it helpful.

If you have questions or comments after reading this white paper, please comment on this blog and we’ll get back to you as soon as possible.

What to Expect from OpenStack Manila Liberty

On October 7, 2015, the SNIA Ethernet Storage Forum is pleased to present its next live Webcast on OpenStack Manila. Manila is the OpenStack file share service that provides the management of file shares (for example, NFS and CIFS) as a core service to OpenStack. Intended to be an open-standards, highly-available and fault-tolerant component of OpenStack, Manila also aims to provide API-compatibility with popular systems like Amazon EC2.

I will be moderating this Webcast, presented by the OpenStack Manila Project Team Lead (PTL), Ben Swartzlander, who will dive into:

  • An overview of Manila
  • New features that are being delivered for OpenStack Liberty (due October 2015)
  • A preview of Mitaka

With Liberty availability due next month, this information is extremely timely; I encourage you to register now to block your calendar. This will be a live and interactive Webcast, please bring your questions. I look forward to “seeing” you on October 7th.

NFS 4.2 Q&A

We received several great questions at our What’s New in NFS 4.2 Webcast. We did not have time to answer them all, so here is a complete Q&A from the live event. If you missed it, it’s now available on demand.

Q. Are there commercial Linux or windows distributions available which have adopted pNFS?

A. Yes. RedHat RHEL6.2, Suse SLES 11.3 and Ubuntu 14.10 all support the pNFS capable client. There aren’t any pNFS servers on Linux so far; but commercial systems such as NetApp (file pNFS), EMC (block pNFS), Panasas (object pNFS) and maybe others support pNFS servers. Microsoft Windows has no client or server support for pNFS.

Q. Are we able to prevent it from going back to NFS v3 if we want to ensure file lock management?

A. An NFSv4 mount (mount -t nfs4) won’t fall back to an nfs3 mount. See man mount for details.

Q. Can pNFS metadata servers forward clients to other metadata servers?

A. No, not currently.

Q. Can pNfs provide a way similar to synchronous writes? So data’s instantly safe in at least 2 locations?

A. No; that kind of replication is a feature of the data servers. It’s not covered by the NFSv4.1 or pNFS specification.

Q. Does hole punching depend on underlying file system in server?

A. If the underlying server supports it, then hole punching will be supported. The client & server do this silently; a user of the mount isn’t aware that it’s happening.

Q. How are Ethernet Trunks formed? By the OS or by the NFS client or NFS Server or other?

A. Currently, they’re not! Although trunking is specified and is optional, there are no servers that support it.

Q. How do you think vVols could impact NFS and VMware’s use of NFS?

A. VMware has committed to supporting NFSv4.1 and there is currently support in vSphere 6. vVols adds another opportunity for clients to inform the server with IO hints; it is an area of active development.

Q. In pNFS, does the callback call to the client must come from the original-called-to metadata server?

A. Yes, the callback originates from the MDS.

Q. Is hole punched in block units?

A. That depends on the server.

Q. Is there any functionality like SMB continuous availability?

A. Since it’s a function of the server, and much of the server’s capabilities are unspecified in NFSv4, the answer is – it depends. It’s a question for the vendor of your server.

Q. NFS has historically not been used in large HPC cluster environments for cluster-wide storage, for performance reasons. Do you see these changes as potentially improving this situation?

A. Yes. There’s much work being done on the performance side, and the cluster parallelism that pNFS brings will have it outperform NFSv3 once clients employ more of its capabilities.

Q. Speaking of the Amazon adoption for NFSv4.0. Do you have insight / guess on why Amazon did not select NFSv4.1, which has a lot more performance / scalability advantages over NFSv4.0?

A. No, none at all.

Next Webcast: What’s New in NFS 4.2

We’re excited to announce our next ESF Webcast on NFSv4.2. With NFSv4.1 implemented on several commercial NFS systems, an established Linux client and a new pNFS Linux server, there is a continued growth of NFS usage in the IT industry. NFSv4.1, first introduced in 2010, meets many needs in the modern datacenter, but there are still technologies and advanced techniques that NFS developers want to deliver.

Join me and J Metz on April 28th at 10:00 a.m. PT as we’ll cover a brief update of where we are with NFSv4.1 and more detail on the proposed features for NFSv4.2 that are currently being ratified at the IETF.  This will be a live, interactive session. Register now and please bring your questions.

If you need a primer on NFS before this event, I encourage you to check our 4-part Webcast mini-series available on demand:

Register today. I hope to see you on April 28th.

 

 

 

 

Cloud File Services: SMB/CIFS and NFS…in the Cloud – Q&A

Cloud File Services: SMB/CIFS and NFS…in the Cloud – Q&A

At our recent live ESF Webcast, “Cloud File Services: SMB/CIFS and NFS…in the Cloud” we talked about evaporating your existing file server into the cloud. Over 300 people have viewed the Webcast. If you missed it, it’s now available on-demand. It was an interactive session with a lot of great questions from attendees. We did not have time to address them all – so here is a complete Q&A from the Webcast. If you think of additional questions, please feel free to comment on this blog.

Q. Can your Storage OS take advantage of born-in-the-cloud File Storage like Zadara Storage at AWS and Azure?

A. The concept presented is generic in nature.   Whichever storage OS the customer chooses to use in the cloud will have its own requirements on the underlying storage beneath it.   Most Storage OS’s used for Cloud File Services will likely use block or object backends rather than a file backend.

Q. Regarding Cloud File Services for “Client file services,” since the traditional file services require the client and server to be in a connected mode, and in the same network. And, they are tied to identities available in the network. How can the SMB/NFS protocols be used to serve data from the cloud to the clients that could be coming from different networks (4G/Corporate)? Isn’t REST the appropriate interface for that model?

A. The answer depends on the use case.   There are numerous examples of SMB over the WAN, for example, so it’s not far fetched to imagine someone using Cloud File Services as an alternative to a “Sync & Share” solution for client file services.   REST (or similar) may be appropriate for some, while file-based protocols will work better for others.   Cloud File Services provides the capability to extend into this environment where it couldn’t before.

Q. Is Manila like VMware VSAN or VASA?

A. Please take a look at the Manila project on OpenStack’s website https://wiki.openstack.org/wiki/Manila

Q. How do you take care of data security while moving data from on-premises to cloud (Storage OS)?

A. The answer depends on the Storage OS you are using for your Cloud File Services platform.   If your Storage OS supports encryption, for example, in its storage-to-storage in-flight data transport, then data security in-flight would be taken care of.   There are many facets to security that need to be thought through, including security at rest, some of which may depend on the environment (private/on-premises, service provider, hyperscalar) the Storage OS is sitting in.

Q. How do you get the data out of the cloud?   I think that’s been a traditional concern with cloud storage.

A. That’s the beauty of Cloud File Services!   With data movement and migration provided at the storage-level by the same Storage OS across all locations, you can simply move the data between on-premises and off-premises and expect similar behavior on both ends.   If you choose to put data into a native environment specific to a hyperscalar or service provider, you run the risk of lock-in.

Q. 1. How does one address issue of “chatty” applications over the cloud?   2. File services have “poor” performance for small files. How does one address that issue? Block & Objects do address that issue 3. Why not expose SMB, NFS, Object Interface on the Compute note?

A. 1. We should take this opportunity to make the applications less chatty! 🙂   One possible solution here is to operate the application and Storage OS in the same environment, in much the same way you would have on-premises.   If you choose a hyperscalar or service provider, for chatty use cases, it may be best to keep the application and storage pieces “closer” together.

2. Newer file protocols are getting much better at this.   SMB 3.02 for instance, was optimized for 8K transactions.   With a modern Storage OS, you will be able to take advantage of new developments.

3. That is precisely the idea: the Storage OS operating in the “compute nodes,” serving out their interfaces, while taking advantage of different backend offerings for cost and scalability.

Q. Most storage arrays NetApp, EMC etc., can provide 5 9s of resilience, Cloud VMs typically offer 3 9’s.   How do you get to 5 9’s with CFS?

A. Cloud File Services (CFS) as a platform can span across all of your environments, and as such, the availability guarantees will depend upon each environment in which CFS is operating.

Q. Why are we “adding” another layer? Why can we just use powerful “NAS” devices that can have different media like NVMe, Flash SSD or HDDs?

A. Traditional applications may not want to change, but this architecture should suit those well.   It’s worth examining that “cloud-ready” model.   Is the goal to be “cloud-ready,” or is the goal to support the scaling, failover, and on-demand-ness that the cloud has the ability to provide?   Shared nothing is a popular way of accomplishing some of this, but it may not be the only way.

The existing interfaces provided by hyperscalars do provide abstraction, but if you are building an application, you run a strong risk of lock-in on any particular abstraction.   What is your exit strategy then?   How do you move your data (and applications) out?

By leveraging a common Storage OS across your entire infrastructure (on-premises, service providers, and hyperscalars), you have a very simple exit strategy, and your exit and mobility strategy become very similar, if not the same, with the ability to scale or move across any environment you choose.

Q. How do you virtualize storage OS? What happens to native storage OS hardware/storage?

A. A Storage OS can be virtualized similar to a PC or traditional server OS.   Some pieces may have to be switched or removed, but it is still an operating system.

Q. Why is your Storage displayed as part of your Compute layer?

A. In the hyperscalar model, the Storage OS is sitting in the compute layer because it is, in effect, running as a virtual machine the same as any other.   It can then take advantage of different tiers of storage offered to it.

Q. My concern is that it would be slower as a VM than a storage controller.   There’s really no guarantee of storage performance in the cloud in fact most hyperscalers won’t give me a good SLA without boatloads of money.   How might you respond to this?

A. Of course with on-premises infrastructure, a company or service provider will have more of a guarantee in the sense that they control the hardware behind it.   However, as we’ve seen, SLA’s continue to improve over time, and costs continue to come down for the Public Cloud.

Q. Does FreeNAS qualify as a Storage OS?

A. I recommend checking with their team.

Q. Isn’t this similar to Hybrid cloud?

A. Cloud File Services (CFS) is one way of looking at Hybrid Cloud.   Savvy readers and listeners will pick up that having the same Storage OS everywhere doesn’t necessarily limit you to only File Services. iSCSI or RESTful interfaces could work exactly the same.

Q. What do you mean by Storage OS? Can you give some examples?

A. As I work for NetApp, one example is Data ONTAP.   EMC has several as well, such as one for the VNX platform.   Most major storage vendors will have their own OS.

Q. I think one of the key questions is the data access latency over WAN, how I can move my data to the cloud, how I can move back when needed – for example, when the service is terminated?

A. Latency is a common concern, and connectivity is always important.   Moving your data into and out of the cloud is the beauty of the Cloud File Services platform, as I mentioned in other answers.   If one of your environments goes down (for example, your on-premises datacenter) then you would feasibly be able to shift your workloads over to one of your other environments, similar to a DR situation.   That is one example of where storage replication and application awareness across sites is important.

Q. Running applications like Oracle, Exchange through SMB/NFS (NAS), don’t you think it will be slow compared to FC (block storage)?

A. Oracle has had great success running over NFS, and it is extremely popular.   While Exchange doesn’t currently support running directly over SMB at this time, it’s not ludicrous to think that it may happen at some point in the future, in the same way that SQL has.

Q. What about REST and S3 API or are they just for object storage?   What about CINDER?

A. The focus of this presentation was only File Services, but as I mentioned in another answer, if your Storage OS supports these services (like REST or S3), it’s feasible to imagine that you could span them in the same way that we discussed CFS.

Q. Why SAN based application moving to NAS?

A. This was discussed in one of the early slides in the presentation (slide 10, I believe).   Data mobility and granular management were discussed, as it’s easier to move, delete, and otherwise manage files than LUNs, an admin can operate at a more granular level, and it’s easier to operate and maintain.   No HBA’s, etc.   File protocols are generally considered “easier” to use.

 

 

New Webcast: Cloud File Services: SMB/CIFS and NFS…in the Cloud

Imagine evaporating your existing file server into the cloud with the same experience and level of control that you currently have on-premises. On October 1st, ESF will host a live Webcast that introduces the concept of Cloud File Services and discusses the pros and cons you need to consider.

There are numerous companies and startups offering “sync & share” solutions across multiple devices and locations, but for the enterprise, caveats are everywhere. Register now for this Webcast to learn:

  • Key drivers for file storage
  • Split administration with sync & share solutions and on-premises file services
  • Applications over File Services on-premises (SMB 3, NFS 4.1)
  • Moving to the cloud: your storage OS in a hyperscalar or service provider
  • Accommodating existing File Services workloads with Cloud File Services
  • Accommodating  cloud-hosted applications over Cloud File Services

This Webcast will be a vendor-neutral and informative discussion on this hot topic. And since it’s live, we encourage your to bring your questions for our experts. I hope you’ll register today and we’ll look forward to having you attend on October 1st.    

 

pNFS and Future NFSv4.2 Features

In this third and final blog post on NFS (see previous blog posts Why NFSv4.1 and pNFS are Better than NFSv3 Could Ever Be and The Advantages of NFSv4.1) I’ll cover pNFS (parallel NFS), an optional feature of NFSv4.1 that improves the bandwidth available for NFS protocol access, and some of the proposed features of NFSv4.2 – some of which are already implemented in commercially available servers, but will be standardized with the ratification of NFSv4.2 (for details, see the IETF NFSv4.2 draft documents).

Finally, I’ll point out where you can get NFSv4.1 clients with support for pNFS today.

Parallel NFS (pNFS) and Layouts

Parallel NFS (pNFS) represents a major step forward in the development of NFS. Ratified in January 2010 and described in RFC-5661, pNFS depends on the NFS client understanding how a clustered filesystem stripes and manages data. It’s not an attribute of the data, but an arrangement between the server and the client, so data can still be accessed via non-pNFS and other file access protocols.   pNFS benefits workloads with many small files, or very large files, especially those run on compute clusters requiring simultaneous, parallel access to data.

NFS 3 image 1

Clients request information about data layout from a Metadata Server (MDS), and get returned layouts that describe the location of the data. (Although often shown as separate, the MDS may or may not be standalone nodes in the storage system depending on a particular storage vendor’s hardware architecture.) The data may be on many data servers, and is accessed directly by the client over multiple paths. Layouts can be recalled by the server, as in the case for delegations, if there are multiple conflicting client requests.  

By allowing the aggregation of bandwidth, pNFS relieves performance issues that are associated with point-to-point connections. With pNFS, clients access data servers directly and in parallel, ensuring that no single storage node is a bottleneck. pNFS also ensures that data can be better load balanced to meet the needs of the client.

The pNFS specification also accommodates support for multiple layouts, defining the protocol used between clients and data servers. Currently, three layouts are specified; files as supported by NFSv4, objects based on the Object-based Storage Device Commands (OSD) standard (INCITS T10) approved in 2004, and block layouts (either FC or iSCSI access). The layout choice in any given architecture is expected to make a difference in performance and functionality. For example, pNFS object based implementations may perform RAID parity calculations in software on the client, to allow RAID performance to scale with the number of clients and to ensure end-to-end data integrity across the network to the data servers.

So although pNFS is new to the NFS standard, the experience of users with proprietary precursor protocols to pNFS shows that high bandwidth access to data with pNFS will be of considerable benefit.

Potential performance of pNFS is definitely superior to that of NFSv3 for similar configurations of storage, network and server. The management is definitely easier, as NFSv3 automounter maps and hand-created load balancing schemes are eliminated; and by providing a standardized interface, pNFS ensures fewer issues in supporting multi-vendor NFS server environments.

Some Proposed NFSv4.2 features

NFSv4.2 promises many features that end-users have been requesting, and that makes NFS more relevant as not only an “every day” protocol, but one that has application beyond the data center. As the requirements document for NFSv4.2 puts it, there are requirements for:  

  • High efficiency and utilization of resources such as, capacity, network bandwidth, and processors.
  • Solid state flash storage which promises faster throughput and lower latency than magnetic disk drives and lower cost than dynamic random access memory.

Server Side Copy

Server-Side Copy (SSC) removes one leg of a copy operation. Instead of reading entire files or even directories of files from one server through the client, and then writing them out to another, SSC permits the destination server to communicate directly to the source server without client involvement, and removes the limitations on server to client bandwidth and the possible congestion it may cause.

Application Data Blocks (ADB)

ADB allows definition of the format of a file; for example, a VM image or a database. This feature will allow initialization of data stores; a single operation from the client can create a 300GB database or a VM image on the server.

Guaranteed Space Reservation & Hole Punching

As storage demands continue to increase, various efficiency techniques can be employed to give the appearance of a large virtual pool of storage on a much smaller storage system.   Thin provisioning, (where space appears available and reserved, but is not committed) is commonplace, but often problematic to manage in fast growing environments. The guaranteed space reservation feature in NFSv4.2 will ensure that, regardless of the thin provisioning policies, individual files will always have space available for their maximum extent.

NFS 3 image 2

While such guarantees are a reassurance for the end-user, they don’t help the storage administrator in his or her desire to fully utilize all his available storage. In support of better storage efficiencies, NFSv4.2 will introduce support for sparse files. Commonly called “hole punching”, deleted and unused parts of files are returned to the storage system’s free space pool.

Obtaining Servers and Clients

With this background on the features of NFS, there is considerable interest in the end-user community for NFSv4.1 support from both servers and clients. Many Network Attached Storage (NAS) vendors now support NFSv4, and in the last 12 months, there has been a flurry of activity and many developments in server support of NFSv4.1 and pNFS.

For NFS server vendors, there are NFSv4.1 and files based, block based and object based implementations of pNFS available; refer to the vendor websites, where you will get the latest up-to-date information.

On the client side, there is RedHat Enterprise Linux 6.4 that includes full support for NFSv4.1 and pNFS (see www.redhat.com), Novell SUSE Linux Enterprise Server 11 SP2 with NFSv4.1 and pNFS based on the 3.0 Linux kernel (see www.suse.com), and Fedora available at fedoraproject.org.

Conclusion          

NFSv4.1 includes features intended to enable its use in global wide area networks (WANs).   These advantages include:

  • Firewall-friendly single port operations
  • Advanced and aggressive cache management features
  • Internationalization support
  • Replication and migration facilities
  • Optional cryptography quality security, with access control facilities that are compatible across UNIX ® and Windows ®
  • Support for parallelism and data striping

The goal for NFSv4.1 and beyond is to define how you get to storage, not what your storage looks like. That has meant inevitable changes. Unlike earlier versions of NFS, the NFSv4 protocol integrates file locking, strong security, operation coalescing, and delegation capabilities to enhance client performance for data sharing applications on high-bandwidth networks.

NFSv4.1 servers and clients provide even more functionality such as wide striping of data to enhance performance.   NFSv4.2 and beyond promise further enhancements to the standard that increase its applicability to today’s application requirements. It is due to be ratified in August 2012, and we can expect to see server and client implementations that provide NFSv4.2 features soon after this; in some cases, the features are already being shipped now as vendor specific enhancements.  

With careful planning, migration to NFSv4.1 (and NFSv4.2 when it becomes generally available) from prior versions can be accomplished without modification to applications or the supporting operational infrastructure, for a wide range of applications; home directories, HPC storage servers, backup jobs and a variety of other applications.

 

FOOTNOTE: Parts of this blog were originally published in Usenix ;login: February 2012 under the title The Background to NFSv4.1. Used with permission.

Update: Want to learn more about NFS? Check out these SNIA ESF webcasts: