Back when I was deputy editor of this magazine my illustrious predecessor, Linda Kennedy, was fond of reminding me that “no one is irreplaceable”.

“Boy, stick your arm in a bucket of water and then pull it out again,” she used to say. “See how quickly the water fills up that hole? That’s how fast you can be replaced.”

And now I’ve replaced her. Which proves her point — sort of. As anyone who ever met Linda can tell you, she’s truly irreplaceable. For over 10 years Linda was the engine that powered CIO in Australia. She grew the magazine from a 32-page insert in the weekly IT newspaper Computerworld and built it into the platinum brand that it is today. She’s a maverick, and hers are big shoes to fill. On some level, I doubt I’ll ever be able to fill them. For one thing, I don’t look very good in heels.

But apart from upbraiding me when I got stroppy as a young journo, Linda did have a point about no one being irreplaceable. No employee should be irreplaceable, especially in an IT department.

When the news first broke in July about Terry Childs, the so-called “rogue” network administrator who locked down San Francisco’s Fibre WAN, I’m sure many CIOs felt at least some glimmer of recognition. After all, rare is the IT shop that doesn’t have too much knowledge invested in one or more key employees.

For those who haven’t heard, Childs is accused of four counts of tampering with a computer, which includes creating secret passwords to San Francisco’s network infrastructure that he wouldn’t reveal and installing software to monitor e-mail from city managers. Costs related to Childs’ hijacking of the city’s network are estimated at $US1 million, and officials are still hunting for a mysterious networking device hidden somewhere on the network.

The manager-techie relationship has always been a stormy one. The two have long struggled to understand and respect what each other does. And every few years the relationship is placed under further stress by collisions between business and technology, from the Y2K debacle to expensive enterprise software to cost-cutting measures like offshoring and outsourcing.

And now, as we’re just beginning to count the overall economic cost of Wall Street’s collapse, it’s a safe bet that IT departments will be squeezed even more in the months ahead. With so much uncertainty and anxiety brought on by a stumbling economy, it’s not surprising that some tech workers — maybe even a few in your own organisation — are simmering with rage in their cubicles and on the verge of a mental meltdown.

This should get CIOs thinking. Whether your network involves a dozen machines or a thousand, do you have chokepoints where one critical worker controls all access? If that worker is laid off, resigns or gets hit by a bus tomorrow, what would you do?