Common ground for Windows and Unix

When you need to share data files between Windows and Unix platforms, you can turn to Network File System (NFS). With NFS, any client can access remote network resources as if they were in the client's native format.

You can host NFS files on any NetWare or Windows NT server, but NFS server software and the data traffic attendant to it can put a heavy load on your network servers. An alternative to weighing down your general-purpose network servers is to install a specialized NFS server. But if you choose to use one of these expensive behemoths, you take on the labor-intensive task of having to load, configure and maintain corresponding NFS client software on every client that must use it.

Luckily, there is a better way -- the NFS gateway. These applications manage resource access between Windows clients and NFS servers. By handling NFS connectivity from a central platform, an NFS gateway obviates installing NFS software on each client.

We compared NFS gateways that run on Windows NT Server to evaluate their relative features and benefits. We lined up products that would not require modifications to existing clients or application software, but would allow clients to perform all tasks in the native client environment.

The products we examined were Hummingbird Communications' NFS Maestro Gateway 6.1.1, NetManage's InterDrive Gateway 5.0, WRQ's Reflection NFS Gateway and Xlink Technology's Omni-NFS Dual Gateway software.

Overall, our comparison contained no slouches. We were pleased with the performance and manageability of all the participants. Each product provided necessary NFS resource access with good performance. And even though all the NFS gateways scaled from a few dozen to thousands of users, Hummingbird's NFS Maestro Gateway scored more points in this area because it scales with the most ease and flexibility.

Thanks to its scalability, many useful management features and thorough support for Network Information Service (NIS) for tracking Unix-based resources, we gave the Network World Blue Ribbon Award to Hummingbird's NFS Maestro Gateway. However, it is important to note that Hummingbird's product is by far the most expensive package for a 100-user license.

Manageability

If an NFS gateway doesn't streamline management, why have it?

Therefore, we weren't surprised when all our entries scored well in this category. They all support the latest version of NFS. NFS Version 3 includes far more management features than previous versions. Each product allowed all clients to be managed from a single console. They also enabled printer sharing between the two operating environments, file and directory browsing, and individual user mapping. All let network administrators define more than one set of access rights for NFS resources, making it easy to restrict access to resources by different types of clients.

But just as important as what the products do is what they don't do: None required the installation of special software on the clients.

In one important management area, however, one product did fall short. NFS gateways from Hummingbird, NetManage and WRQ let you configure and manage multiple gateways from a single console using their remote administration tools. Disappointingly, Xlink's Omni-NFS Dual Gateway lacks a remote administration feature.

As for installation and use, all installled quite easily and employed the familiar Windows interface. However, we have one complaint: NetManage's InterDrive Gateway 5.0 had practically no paper documentation; we like the ready availability of a printed manual.

NOS integration

We expected the basics in terms of network operating system (NOS) integration. TCP support and NFS file browsing were the bare minimum requirements that we placed on each participant. We got this basic level of support from all the products.

Beyond that, we thought the key to easy and elegant integration with NOSes was support for NIS, a distributed database that lists available resources within NFS. Network managers use NIS to define the NFS resources available to each user. To effectively use all the NFS resources available to a given user, the gateway must fully support NIS.

Microsoft Windows offers name resolution via Domain Name System (DNS) or Windows Internet Name Service (WINS), but not through NIS. This means that if your network doesn't support DNS or WINS, your Windows clients won't have automatic access to NFS resources without NIS.

Without NIS support in the gateway product, you would have to define the resources manually for each client or install additional client software.

Hummingbird's NFS Maestro Gateway had an advantage in the area of NIS support. Its software supports client browsing of NIS maps, automated drive mapping and more. In other words, it lets Windows clients browse and access NFS resources as easily as Unix clients.

Also worthy of note in the NIS support category was NetManage's InterDrive Gateway 5.0, which manages network connections using the familiar Windows control panel, Windows Explorer, Network Neighborhood or even an old-fashioned MS-DOS window.

While NOS integration begins with NIS support, it doesn't end with it. Flexibility is also important. For example, if the gateway is restricted to one-way access, only Windows clients can access Unix resources, but not vice versa. Xlink's Omni-NFS Dual Gateway stood out because it is bidirectional, which allows Windows and Unix clients to have access to files across NT and Unix servers.

Scalability

For an NFS gateway product, scalability on the server side means being able to accommodate a growing number of clients. With their centralized management and gateway server-based design, all the participants in this comparison are pretty scalable from a server perspective. However, scalability on the client side means allowing a client to establish and maintain many connections to a growing number of Unix resources. This can be tricky because only 26 drive letters are available to any Windows NFS client.

Xlink's Omni-NFS Dual Gateway accommodates client scalability by allowing one drive to retain multiple drive letters that can each have different access rights. Hummingbird's NFS Maestro Gateway implements deviceless connections, allowing clients to connect to NFS file systems without reserving a drive letter for that connection. This worked smoothly during our testing and freed device letters for other types of connections. What's more, NFS Maestro Gateway is the only product in our sample that supports the WebNFS protocol for

Web-based resource access and sharing.

The other companies plan to add WebNFS support to their products in the near future.

Performance

Performance was fairly equal among the products we tested. The greatest variation in task completion time across various platforms was less than 7%.

In addition to raw throughput measurements, we looked at a couple of gateway design elements that affect performance and may give certain products an advantage in large, complex and very busy networks. The first design element was client architecture. By its very nature, NFS gateway software can't allow the direct, rapid access to NFS resources that a well-tuned piece of NFS clientt software can.

Just for fun, we compared the performance of NFS gateway systems with that of NFS clients working directly with NFS servers. We used Hummingbird's Maestro NFS Gateway Client software. As you can imagine, Hummingbird's multithreaded 32-bit client running at Ring 0 was faster at file access than any of the NFS products -- even Hummingbird's NFS Maestro Gateway. However, performance of the client wasn't so great that it justified the additional complexity and management headaches of loading NFS client software on each desktop.

The second design element we considered was automatic performance tuning of the NFS gateway to optimize throughput at times of peak usage. NetManage's InterDrive Gateway 5.0 has the most impressive autotuning feature; it optimizes throughput not only for each host, but also for each connection. The autotuning features of WRQ's Reflection NFS Gateway came in a very close second.

Security

If an NFS gateway product enforces consistent file permissions, it can use the security features of the NOS environment in which it operates. NIS plays an important role in ensuring that the group ID numbers and user ID numbers that Unix employs to identify files remain synchronized among the hosts and NFS gateway. In short, strong NIS support ensures that user access permissions to a file don't change as the file is saved from host to host.

All the participants handled file permissions adequately, though Hummingbird's NFS Maestro Gateway, the product with the most thorough NIS support, scored the best in this category. However, NetManage's InterDrive Gateway 5.0 was equally impressive for its similar use of Microsoft security on the Windows side, along with NIS and PC-based NFS authentication routines on the NFS server side. This means that authentication takes place at the Windows client and again at the NFS server.

When we looked at each product as a whole, we realized we would recommend any of them depending upon the environment in which they would operate. Xlink's Omni-NFS Dual Gateway, with its bidirectional client support, is a great choice for networks with Unix clients trying to access NT resources and vice versa. Because it was easy to deploy and had good client-side security, we liked NetManage's InterDrive Gateway 5.0 for smaller networks with exclusively Windows clients. WRQ's Reflection NFS Gateway was fast and scalable, making it good for large networks. But in terms of performance, manageability, scalability and ease of use, the overall winner for networks of all sizes was Hummingbird's NFS Maestro Gateway.

Scorecard

 Manage-ability 40%NOS integration 20%Scalability 20%Performance 10%  Security   10%TOTAL
NFS Maestro Gateway 6.1.19 x .4 = 3.69 x .2 =1.89 x .2 = 1.88 x .1 = 0.89 x .1 = 0.98.9
InterDrive Gateway 5.09 x .4 = 3.68 x .2 =1.68 x .2 =1.68 x .1 = 0.89 x .1 = 0.98.5
Reflections NFS Gateway9 x .4 = 3.68 x .2 =1.67 x .2 = 1.48 x .1 = 0.89 x .1 = 0.98.3
Omni-NFS Dual Gateway7 x .4 = 2.88 x .2 =1.67 x .2 = 1.47 x .1 = 0.79 x .1 = 0.97.3

Note: Products are ranked on a 1-10 scale in each category, then multiplied by the weight in each category. These are added to give a total score.

Net Results

NFS Maestro Gateway 6.1.1

Hummingbird Communications, Ltd.

1 Sparks Avenue

North York, Ontario, Canada M2H2W1

(416)496-2200

Fax: (416)496-2207

Web site

$11,600

Excellent NIS integration

Supports WebNFS protocol.

Highest price of all participants

InterDrive Gateway 5.0

NetManage, Inc.

10725 North De Anza Blvd.

Cupertino, Calif. 95014

(408)973-7171

Fax: (408)257-6405

Web site

$9,000

Pros: Excellent autotuning features; Strong security

Cons: Extremely little paper documentation

Reflection NFS Gateway

WRQ, Inc.

1500 Dexter Avenue North

Seattle, Wash. 98109

(800)872-2829, (206)217-7100

Fax: (206)217-0293

Web site

$7,200

Pros: Excellent autotuning features

Omni-NFS Dual Gateway

Xlink Technology, Inc.

1546 Centre Pointe Drive

Milpitas, Calif. 95035

(408)263-8201

Fax (408)263-8203

Web site

$6,500

Pros: Bi-directional, allowing Windows and Unix clients access to files on both NT and Unix servers; Low price

Cons: No remote management administration feature

This story, "Common ground for Windows and Unix" was originally published by Network World.

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