An IMAP book and measuring power use

A book on high performance IMAP servers and how much power does dimming a laptop screen save?

Many of the books sent to me in hopes that I will review them are, well, irritating. They adopt a cute "we're all in this together except I'm the expert and you're the noob" tone, and if they are discussing almost any networking topic, they start out with a dissertation on TCP/IP. It's a clever ploy as that can take what would otherwise be a slim tome and give it enough heft to justify a price tag of $29.95 or whatever.

Be that as it may, occasionally a book appears that I think is worth the price tag and covers stuff that is actually useful. Which brings me to The Book of IMAP: Building a Mail Server with Courier and Cyrus, by Peer Heinlein and Peer Hartleben.

The Book of IMAP is really a how-to guide for anyone wanting to build not just an IMAP server, but one that delivers a high-performance, high-reliability service.

Courier and Cyrus, the free, open source systems discussed, are among the most commonly used IMAP servers, and the authors provide useful guidance on the pros and cons of both. They also cover the configuration issues that implementers need to consider such as the underlying hardware, file systems and communications architecture. This is not a book for noobs so if you don't have some familiarity with IMAP and messaging in general, it may cause your brain to fuse. Highly recommended.

And speaking of receiving things in the mail, I was also recently sent a device for measuring power consumption – the Watts Up energy meter manufactured by Electronic Educational Devices. At about the same time a friend asked me an interesting question: How much power does dimming the backlight on a laptop display save? This would have been the perfect opportunity to test the meter except for the fact that when he sent me the question it was 1 a.m. and the meter was, at the time, plugged into my rack in the computer room.

On a whim I pitched the question to my friends on a listserv and the next morning there was an answer from someone far more qualified in the esoterica of power measurement and management and who also had the same energy meter.

He used the Watts Up to evaluate the power consumption of an IBM Thinkpad X60 and found that at full brightness the laptop consumed 12 watts while at minimum brightness it was drawing between 8 and 9 watts.

This means a machine powered on all day with the screen dropping to low brightness for, say, 18 hours per day and with electricity at roughly $0.10 per kilowatt hour, would save about 88 watts or $0.0064 per day for power, which is about $2.34 per annum. Multiply that by the gazillion laptops in your organization and that soon turns into real money.

The same person went around measuring other gear and found the average PC appeared to burn around 40 watts (about $28 per year) while a small form factor machine was using about 20 watts (that's about $14 per year). He also mentioned that the newer DLink Gig switches have smart power management and that they "turn down ports when not in use and only supply enough power to match the length of the cable run.” This means that they consume about half the power of the prior generation of the same switch.

The Watts Up meter is a clever device that comes in four models and they all measure power use in terms of volts, amps, watts and cost. The base model costs $96 while the Pro and Pro ES models are $131 and $196 respectively and have USB connections for computer monitoring (the latter includes monitoring software). The .Net version at $236 also has an Ethernet interface and a built-in Web server. Recommended.

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