Slim Servers

All of my colleagues love Dell servers. I'm jealous because I always end up settling for commodity hardware, which is certainly cheap, but definitely lacking in elegance. On a recent visit to my alma mater, Sonoma State, I was shown a whole stack of Dell 2450s running Linux, serving pages for departmental Web sites. The staff told me that Dells are boring because they rarely break down. Building on such a reputation, this spring Dell shipped two zippy rack mounts—the PowerEdge 1650 (a 1U Web server) and the 2650 (a 2U). I decided to give them a whirl. The ones Dell sent me were preinstalled with Red Hat Linux 7.2 and its suite of popular open source server software.

Dell also offers Microsoft Windows 2000 options: Windows 2000 Server and Windows 2000 Advanced Server. Dell supplied a factory-install Windows NT Server 4.0 option for five years, but as of July 1, this option is no longer available. DNS and TripWire capabilities are available with Linux only. Dell adds a rapid deployment application and Web-based system management software to each operating system. If you actually read the instructions after opening the box, you can be serving pages in about ten minutes.

The 2650 is available with one or two Intel Xeons. The test unit had dual 2GHz CPUs. The 1650 uses one or two Pentium III processors, and our test unit had dual 1.13GHz CPUs.

The Hardware

I've tested many rack mount servers based on generic commodity server parts, and I've noticed that system integrators usually have a hard time squeezing standard motherboards and power supplies into slim cases. Typically, they end up sacrificing features like redundant power or drive bay space.

Dell has historically worked around these limitations by designing its own motherboards and cases to integrate perfectly. With Dell machines, you don't need extra cables to connect drives and power supplies—everything snaps together. Dell's careful system designs result in hardware that's easy to work with.

Both servers cram an amazing collection of hardware features into a very small space. They both have removable Ultra SCSI drive bays (three on the 1650 and five on the 2650) and accommodate dual CPUs and dual redundant power supplies. They each have two Gigabit Ethernet NICs and PCI card slots—three on the 2650 and two on the 1650. They also have thin, space-saving CD-ROM and floppy drives that look like they were borrowed from Dell's laptops.

Many small touches show that Dell engineers understand the realities of working in a server room. For example, each server has keyboard/monitor/mouse jacks on both the front and rear panels so you don't have to run back and forth between the front and rear of the racks.

In addition to the extra drive bays and more powerful processors, extra features on the 2650 include a small LCD display for showing system status, and a built-in embedded remote access (ERA) controller. The only notable feature on the 1650 that isn't present on its bigger sibling is an external SCSI connector on the rear panel.

The 2650 case accommodates two power supplies that can be installed through the rear panel. The 1650 requires access to the top to install its power supplies, but the fact that Dell managed to squeeze in space for dual supplies makes this a unique 1U server. Either system will run on one supply. If power is lost from one supply, an alert light blinks and the system can optionally send you notification. Because the supplies are hot-pluggable, you can replace a bad supply without rebooting.

Both cases are deep at 27 inches, and less rigid than I would like. When the case flexes, the motherboard flexes, too. As long as you don't move them around much it won't really matter, but if you have any choice, use four post racks to give the cases more support.

Remote Control

If you've ever had a remotely co-located system lock up on you, you know that if you can't log in, you can't reboot it. One solution I like is to plug my servers in to a power strip with a Web interface on it—like those from APC. Dell has built power management into these servers with its ERA controller. (As mentioned above, it's standard on the 2650 and an option on the 1650.)

The ERA is an embedded Web server with its own 10/100 Base-T Ethernet port. It's powered up and available whenever the server is plugged in, even when the main system is shut down. You log in with a browser. If the server is up and the operating system is running, you can perform clean shutdown or restarts from the ERA. In the event that the system is crashed or powered off, you can still turn the ERA on and off. The embedded controller also has access to the motherboard and case sensors, so you see the status of all sensors from the same browser connection. For example, you can log in to the ERA and check the status of a crashed system before deciding on appropriate action.

Excellent Software

The servers were installed with PowerEdge Web Server 3.1, an enhanced version of the standard Red Hat 7.2 server suite. The main enhancements include Dell's OpenManage and Web Assistant packages; Courier mail as a much more manageable replacement to Sendmail; and the Tomcat Java server. Although the PowerEdge software comes preloaded, the included CDs have a custom installation script to make reloading it simple.

You can handle most day-to-day system administration with the Web Assistant interface, and you can access hardware related information with the OpenManage interface. Both are SSL-secured.

The Web Assistant screen layout is like the basic Explorer layout. Web Assistant can be used to perform basic system operations including viewing logs, scheduling and performing backups (by copying files across the network), system upgrades via Red Hat packages, network configuration, and of course, managing services.

If you host multiple virtual domains, you can use Web Assistant to create and manage each domain. A tiered permission system gives limited user access and allows for site administration.

Web Assistant works directly with the standard system configuration files, so for more flexibility, you can mix management via Web Assistant with traditional editing of the text files.

Because PowerEdges are intended to be used as Web servers, Web Assistant is designed to handle only Web server tasks. If you need to perform tasks outside its purview, you'll have to use a command shell. Web Assistant is very good at what it does, but it doesn't try to do everything, either. Many packages are preinstalled on the PowerEdge servers that are beyond Web Assistant's control. These include NFS, Samba, NTP, NIS, and Squid.

OpenManage features the same screen layout as Web Assistant. With it, you can check on the same system sensors that are available to the ERA embedded processor. The key difference between ERA and OpenManage is that OpenManage runs on the Linux system itself. Unlike ERA, you can configure OpenManage to use system resources to send alerts if sensor parameters drift out of range. For example, I set it to run a script that will email me if anyone removes the front bezel from the system.

If you already have an SNMP-based management system in place, you can ignore the OpenManage Web server and enable SNMP support on the PowerEdge server. SNMP support comes preinstalled, but it's turned off for network security.

Steady Improvement

Upon receiving the servers, I opened up the cases and looked inside. Even if they came with no preinstalled software, the basic hardware alone on the PowerEdge servers is a great value. While the 2650 is an incremental improvement over the 2450 and 2550 models, the 1650 is the first time any vendor has managed to squeeze dual redundant power supplies into a 1U form factor.

Both the 1650 and the 2650 have a separate Web management embedded processor for cold starts—an unequalled feature. The closest feature to this one on a competing system is the serial port management system on the Sun Netra X-1, but that takes extra work to roll out. (You would need a scheme that supported one serial port for each Netra, like a RAS.) And it's somewhat unusual, but not unique, to squeeze so many drive bays into rack mount servers and still have CD-ROM and floppy drives—there are three in the 1650 and five in the 2650.

Of course, cramming two 2GHz Xeons into a flat case required Dell to install high capacity fans. However, the only serious complaint I have is that the fans in the 2650 are very loud. Dell assured me that a pending firmware upgrade will let you turn down the fans. (The 1650 already has variable speed cooling fans implemented.)

If you're deploying a large farm or want to use advanced features, you'd probably install your own software configuration. The standard Dell software doesn't support any clustering, load balancing, or centralized management scheme. Dell does offer a high-performance clustering product built around the 1650/2650 servers. But if you only need a few servers, the standard Dell/Red Hat software combo is an excellent starting point.

Brian is cofounder of Harbro Systems. Reach him at [email protected].