Lee Kimber

Currently using eight NSLU2s as low-power - but otherwise conventional - servers, including:

1. Anti-spam IMAP/POP3 email server (using SpamAssassin, Postfix, Cyrus-Imap, Cyrus-SASL) and filtering proxy server. How to: Set up a low-power anti-spam email server.
2. Lighttpd and MySQL-based web server with PunBB forum and Wikka wiki
3. Primary Bind9-based Dynamic DNS server, with DHCP updates. How to: Build the Primary DNS Server. How to: Configure DHCP to update Dynamic DNS
4. Dual sensor digital temperature logger. How to: How to Add a USB-to-OneWire Adapter and DigiTemp
5. Windows file server (two 160Gb HDDs)
6. Asterisk telephony/VoIP server (running on SlugOSbe)
7. MySQL server (running on SlugOSbe)
8. OneWire battery-bank temperature and voltage monitor server (running owfs on SlugOSbe). Powers down other servers if battery bank goes under-voltage Current averaged voltages
9. Velleman K8055 USB Interface Board controller. How to: How to Add a Velleman K8055 USB Interface Board

This installation is running an email server, proxy server, intranet web, Dynamic DNS and DHCP server, and file server on around 25 Watts, compared with the power consumption of a single, traditional office server's 300 Watts minimum.

Power source is a 320Ah 12V battery bank. It is reduced to 5V by ten paralleled, switched mode, 7A DC-DC converters. They are isolated by Schottky diodes to create a common rail supply of up to 70A at 5.5V. They will run for two hours from a single 80Ah car battery. The voltage monitor server powers down the servers before the battery fully discharges.

The battery charge controllers and associated bits were built for less than £40. Here's how.

And once you have 12 volts on tap, you have to test its delivery into a load. And a 12V coffee filter machine is a great way to start.

Reference

Phil's real-world experience of running low-powered NSLU2s in the UK is detailed here.