Techno Dabbler

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Tuesday

06

October 2015

Dell 2161DS-2 : How not to choose a KVM

by Alexandre Denault

Dell 2161DS-2 : How not to choose a KVM

A KVM Switch is a device that allows a keyboard, a video monitor and a mouse (hence the name) to be shared across multiple computers. This particular model, the Dell 2161DS-2, is commonly used in server rooms, where large numbers of servers only require a monitor and keyboard for troubleshooting. It supports up to 16 computers on its own, and 256 using add-on modules.

Fundamentally, the 2161DS-2 is a solid device. Released in 2007, the unit still shows popularity among the used market. However, remote control is severely flawed and limits how it can be used in the long term.

One of the most common problem found in KVM is bulky cables, especially when hooking up several keyboard, video and mouse cables to a central location. The 2161DS-2 solves this problem by using system interface pods (sip) to hookup the servers using regular CAT5 cabling. Cable bulk behind the KVM is reduce to a third, and managing a single cable per machine is a lot less error prone.

Using the 2161DS-2 is fairly straight-forward, double tapping the CTRL key brings up the On-Screen Configuration and Activity Reporting (OSCAR) control menu from which you can configure the switch, or select the computer to control. Additional configuration options are available if you hookup the switch to a serial port.

The most important feature of a KVM switch in a server room is network connectivity, for remote configuration and control. It one of the "must-have" feature when the server room is located several hundred miles from the home office. Unless a server features an integrated out-of-band management solution, a remote KVM also is the only way to remotely configure low level aspect, such as the BIOS or the RAID, of that server. In the case of the 2161DS-2, remote configuration is avaible in a web interface that works well, but is a bit archaic by modern standard. However, the biggest of flaw of the device is the remote control interface, which highlights how a poor Java implementations can ruin a device.

Remote control is implemented using a Java Webstart application that requires Java 1.6. Some people have made it work using Java 7, but Java 8 is completely incompatible. If you are using MacOS X, you are out of luck since the operating system is not supported. Under Windows and Linux, you might get it working if you can find an old version Java. However, you will also have to deal with security problems since its code signing certificate is expired.

A KVM is a piece of hardware that should not need to be replaced unless defective. Using Java effectively puts a timer on the device, disabling features as time passes. This is a common problem with all KVM using Java, including the more popular models from Avocent and Raritan, two of the biggest names in KVM. In fact, this particular Dell switch is an Avocent switch hat was rebranded and sold by Dell.

Using a known protocol to implement remote control, such as VNC, effectively eliminates this problems. This explains the long lasting popularity of the ADDERLink ipeps, which was released in 2007 but still fetches a high price.

Ultimately, the Dell 2161DS-2 fails as a remote KVM because this feature becomes more difficult to use with time. Given that this device has reached its end-of-line (EOL), it's unlikely that a firmware will be released to address these issues.

When choosing a remove KVM solution, do not neglect evaluating the technology used to implement the remote control solution. This single aspect might dictate the longevity of your investment.

Alexandre Denault
Alexandre Denault

Veteran software developer and holds a PhD in Computer Science. Avid computer enthusiast (geek) who has been dabbling with technology ever since his Dad brought home an 8086 computer.

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