Welcome to wireless network-attached storage

ServeLinux's Xgate provides file sharing for Windows, Mac, and Unix/Linux clients-for less than $1,000.


The governing dictum for delivering a winning IT appliance to market is "Good stuff-cheap." The appliance construct is simple: Solve an annoying if not complex IT problem with an easy-to-configure black box.

Network-attached storage (NAS) devices set off the appliance firestorm. Following the NAS success, appliance mania has spread to Web servers, cache servers, and firewalls, with storage devices playing a pivotal role in all of these appliances.

Besides featuring ease of use, an appliance needs to carry a rock-bottom price tag, which makes client-access licenses taboo. That's a prescription for open source code, which explains why Samba, Apache, and either Linux or FreeBSD underpins many NAS servers. As a result, Booz Allen & Hamilton projects that Linux appliance server revenue will be about $3.8 billion in 2003.

ServeLinux Networks comes at the NAS appliance market from an interesting perspective. The company has been building appliance-like 1U and 2U turnkey rack-mount Web servers for ISPs. What distinguishes these servers is their browser-based SLASH Console, which enables non-technical staff to set up and manage domains and clients for Web hosting, as well as configure DNS, FTP, and e-mail.

Sporting a price tag of less than $1,000, Serve Linux's Xgate Wireless DSL Server would be an interesting competitor if all it did were provide file and print sharing for Windows clients. But this is the least of what this appliance can do.

Figure 1: Webmin can be used to control a wide variety of server programs such as FTP, Apache, DHCP, and DNS. In particular, the Bootup and Shutdown Module controls the initialization scripts stored in /etc/rc.d. This is important, since neither NFS nor Appletalk file sharing is configured on the Xgate to start automatically.
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The Xgate server provides file sharing for Windows, MacOS, and Unix/Linux clients. For Windows clients, the Xgate comes with Samba. For Unix clients and PCs and Macs running packages such as Shaffer Solutions' DiskAccess and Thursby Software's MacNFS, there is NFS. The first surprise comes in the form of full support for normal Mac clients via the open source packages netatalk, which share disk volumes and printer spools via AppleTalk and MacGate and allow the Xgate to route existing Mac services.

As a standard feature, the Xgate comes with an IEEE 802.11b Wireless Access Point built into the server. For years, the number of knowledge workers who use a laptop as their main computing device has been growing rapidly. Initially, when these devices were merely luggable, the big connectivity issue was getting a fast modem to dial up to the network when you were on the road. Now, the new generation of super-slim laptops has created a new twist on the connectivity issue: how to stay connected in the office when you are walking around.

In its default configuration, the Wireless Access Port-wlan0-supports wireless clients on a local subnet that Xgate assigns via DHCP. The 802.11b protocol-the "b" was added in 1997 to indicate 11Mbps throughput-operates within the 2.4GHz ISM band with 14 channels. International regulatory agencies such as the FCC in the U.S. and ETSI in Europe determine which channels are available. Since nearly all countries allow use of channel 10, this is the default channel for the Xgate Wireless Access Point.

Figure 2: In theory, any browser that supports tables and forms can be used with Webmin to perform routine system administration tasks. Nonetheless, we were unable to launch the Java applet for the File Manager module on a Mac client running OS X and IE 5.1 for the Mac. As its name implies, this module provides a means to navigate the Xgate's directory tree and edit files.
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With the growing buzz over Bluetooth, it's not too surprising that the wireless industry would also jazz up the 802.11b moniker with a new Wi-Fi marketing logo. Devices that sport the Wi-Fi logo have successfully passed the industry group's tests for interoperability. Using Wi-Fi-branded network cards (we used Lucent's ORiNOCO cards) it's quite easy to install an ideal wireless work environment for a department or a small business. The net result is that knowledge workers can take full advantage of their portable computers: They can move to where their work takes them while maintaining continuous network access.

Accessing the Internet via the Xgate, we used www.bmwfilms.com to test Xgate's ability to keep streaming video streaming as a quick first test before getting into serious file-transfer benchmarking. The access point's signal strength held connection speed to a rock-solid 11Mbps throughout our offices.

We decided to up the ante by walking out of the office and down a long corridor to the building's central atrium. We didn't miss a frame. So we went down one flight of stairs and out the back door to a patio. At last the Xgate blinked. For a moment, throughput dropped to 4Mbps but then quickly recovered.

With all this technology, the key question is: Can a non-technical member of the office staff manage this appliance? The answer to that question is a resounding "not exactly." While an amateur will be lost trying to manage the Xgate, a knowledgeable power user or junior systems administrator will have no problem configuring services that would normally require an expert Linux guru.

Remarkably, putting the Xgate up on the network in good working order is just as easy as unpacking and plugging in a Mac. ServeLinux Networks pre-installs Turbo Linux on the server and has written an initial three-step install script, which runs on the first boot up. This is the only time that it is necessary to have a keyboard and monitor attached to the server.

The first screen inquires for the server's local IP address. The install script then suggests entries for the network mask as well as addresses for a gateway and DNS server. The next screen asks for the full hostname of the server. The third screen asks to confirm the information entered on the first two. That's it. A quick 1, 2, 3 and the server reboots.

The tasks are deceptively simple. If you are as untrusting as InfoStor Labs, you'll leave a keyboard, mouse, and monitor plugged into the Xgate for contingencies, which would be a mistake. Leaving a keyboard and mouse plugged in created a resource conflict with our wireless access point software. The access point hardware came up transmitting a very strong signal, which had all of the wireless clients synching up at the full 11Mbps. Everything appeared to be in order, except the Xgate could not process an access point interrupt.

Figure 3: Typical sequential access reads of the NFS volume via DiskAccess NFS were in the neighborhood of 6MBps on a laptop when connected on the wired LAN (left). When we switched to the wireless LAN (right), sequential throughput declined in line with network parameters and measured 700KBps.
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Once the Xgate has been configured and the keyboard, mouse, and monitor are unplugged, the appliance can be managed remotely using Telnet, the Open Source browser-based Webmin utility sponsored by Caldera Systems (www.web min.com) or ServeLinux's browser-based SLASH (ServeLinux Administration Server Help) Console. By default, Xgate boots up with an IPchains-based firewall configured to permit Telnet and Webmin access only from the local network.

The basic requirement to run Webmin is a Java-enabled browser and Java script. For added security, Webmin uses the secure HTTP (HTTPS) protocol. As a result, all communications between the administrator and server are fully encrypted and secure.

It should be noted, however, that Webmin is not for the neophyte user of Linux. Nonetheless, Webmin makes Xgate an ideal foil for a local integrator to manage numerous SOHO clients outfitted with Xgates.

We began by configuring our NFS shares with Webmin. Next, we calibrated disk access performance at Windows 2000 clients when connected on the wired LAN. To test read performance on the NFS volume, we used InfoStor Labs' islfileload benchmark and DiskAccess, NFS client software from Shaffer Solutions. This benchmark reads a file-200MB for these tests-sequentially, randomly, or in a pattern designed to simulate database activity. Since sequential access is by far the most typical and technically recommended use for NFS shares, there was no question about performing this test. However, as a means of identifying other key performance characteristics, we ran a database simulation as well.

In our first test, we ran our islfileload in sequential mode. We repeated the test with different-sized reads ranging from 2KB to 64KB. Most Windows applications access 8KB blocks while many system utilities use 32KB blocks. Throughput ranged from just over 5MBps for 2KB reads up to just over 6MBps with 64KB reads.

Next we ran our database simulation. This benchmark uses 8KB reads distributed in a pattern that simulates database activity. Here we got our first big surprise: With the previous version of DiskAccess NFS, performance on reads was a bit erratic and averaged only about 2MBps. With the new version, performance was very stable and averaged 3MBps.

Next, we deactivated our 100Mbps Intel card and started up the ORiNOCO wireless network interface card. Here the topology of 802.11b and the Windows persistent network client capability made mobility a snap. Going mobile could not be simpler or the performance penalty be reduced to lesser insignificance.

We then repeated the islfileload benchmark on the NFS volume. With linear access, the performance reduction was right in line with theoretical expectations. On the 11Mbps wireless LAN, read throughput was now approximately 700KBps. Similarly, database access held steady at 500KBps.

Our only disappointment in wireless testing occurred with the Mac. From a Mac OS 9 client, connecting to the Xgate via the Chooser is totally transparent to the user. Nonetheless, as with Windows, the Mac's OS 9 cannot directly access NFS volumes without additional third-party software. We had anticipated that the situation would change with the BSD/Mach-based Mac OS X. Basic connectivity actually turns out to be slightly less with the initial OS X release.

The classic Chooser has been replaced with a "Go To" network applet that functions much like the old Chooser. Unfortunately, this applet could not discover any file servers not actually running the Mac OS, and that includes both Windows NT/2000 servers running Apple Share and the Xgate. It was possible, however, to attach to these servers under Mac OS X by entering the server's network ID.

Unfortunately, we could not attach to an NFS server, even with direct identification. There is no GUI NFS connectivity, which left us scrambling to use the terminal application to do it at the very un-Mac-like command line. But even that method is quirky and for gurus only.

The software that really unleashes the power of the Xgate is ServeLinux's SLASH Console. This console provides an intelligent browser-based front-end with which to configure a number of complex tasks. The SLASH Console does not have complicated commands or syntax to learn. Most operations, including CGI, PHP, and even FrontPage extensions, can be done with a mouse click. Because SLASH was created with ISP administration in mind, routine SLASH tasks include managing multiple domains and creating mail accounts, mail redirects, and auto responders with the qmail mail server software that comes with Xgate.

When logged into SLASH as an administrator, three buttons are always displayed on every page: Clients, Domains, and Server. These buttons link to the client administration page, the domain management page, and the server management page, providing the basis for a powerful administration tool.

For small businesses, this may sound like cracking open a peanut with a sledgehammer. Nothing could be further from the truth, however. SLASH harnesses the power of Linux and empowers the existing IT staff to manage all their e-mail and hosting requirements in-house. No longer will technical skills be an issue that may limit a company's online presence. In a matter of minutes, an in-house administrator can set up multiple domains for multiple lines of business and provide each line of business with its own e-mail and Web identities.

Jack Fegreus can be contacted at jack.fegreus@e-open.ws.

InfoStor Labs scenario


Under examination

  • Wireless NAS appliance server What we tested
  • Xgate wireless DSL server (www.servelinux.com)

How we tested

  • Lucent's ORiNOCO Wi-Fi Silver card (www.lucent.com/orinoco)
  • DiskAccessNFS for Windows (www.ssc-corp.com)

Key findings

  • Webmin and SLASH greatly simplify server configuration; however, a base-level understanding of Linux is an absolute requirement.
  • The default configuration does not initiate either Appletalk or NFS file sharing.
  • The embedded Wireless Access Point can provide 40-bit WEP security; however, encryption is not enabled by default.
  • Streaming-video performance to wireless clients was exceptional, and the extended range proved to be an added bonus.
  • NFS access performance on the wireless LAN matched theoretical expectations.

This article was originally published on September 01, 2001