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Low-power servers: Soekris computers

After running several servers full-time for a while - a file server, a mail server, a web server and a firewall - I became increasingly aware of the amount of power used. Even small-form-factor Dell PCs burn a fair amount of power if they're on full time. They also occupy space, and they make heat and noise.

Many modest server applications require reliability rather than speed, so the Soekris range of tiny, low-power computers is ideal. These are specially designed for embedded applications. You can boot them from a Compact Flash card, or over the network with PXEBOOT, or you can install a hard disk. There is also a USB port but the BIOS can't boot from it. You can specify up to eight Ethernet ports (ideal for firewalls), and the console is an RS232 port rather than a video card, making remote management easy. Various metal cases are available, ranging from tiny paperback-sized cases to 1U rackmount versions.

At the moment I run a Soekris net4801 as a firewall, with a Soekris net5501 about to be installed as a mail & DNS server. The 4801 boots from CompactFlash while the 5501 boots from a 2.5 inch hard disk. I chose the 100GB Hitachi E7K100 hard drive because it has the convenient size of a laptop drive, but it's a special version designed for 24*7 server running, so it should give longer life. Standard laptop drives are not really suitable for use in servers, as the battery-saving features cause too many start/stop, load/unload cycles, adversely affecting reliability.

As for power consumption, the net4801 comes in at something like 7 watts, while the net5501 (with its hard disk) is still under 10 watts. The machines have on-board voltage regulators, so they tolerate a wide range of DC power supply voltages, which would be handy if running away from mains power.

The net4801 runs totally silently, while the net5501 is almost silent (the hard disk is very quiet indeed).

Here are some useful links for Soekris computers.

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