Linux lover consumed a quarter of the network

Who, Me? Ah, gentle reader, we find ourselves once again at that juncture of the week we call Who, Me? in which your fellow Regizens' tales of technical not-quite-competence brighten an otherwise dull Monday.

This week our story comes from "Charlie" who, some quarter of a century ago, was working on his PhD at "a large tertiary education institution on the south coast." The south coast of what? He doesn't say. Charlie is an enigma.

Charlie shared an office space with four other students, each of whom had their own desk with their own computer. Charlie's PC was running Windows NT4, but his dearest wish was to run Debian Linux like all the cool rebellious kids.

The problem was that the Debian installation required "something like a dozen CD-ROMs." These could be had by downloading from a federation of servers called Sunsite, which had an outpost nearby. Unfortunately, the internet connection in Charlie's office was slow and unreliable at the best of times, even when it wasn't being shared four ways.

Then Charlie had a brainstorm. Sunsite supported not only the FTP protocol, but also NFS, which of course had all sorts of tricky ways of maintaining and restoring itself over dodgy connections. Slow, to be sure, but at least it would download eventually.

All Charlie had to do was mount Sunsite as an NFS share, and copy the disk images to a local drive. That was where the quirks of NT4 came in, and this proved too complex a task.

Not for Charlie, though. His roomie, who he's asked us to call "Martin" so we will, was already running Linux and allowed Charlie shell access to his machine. Charlie used that to copy data from the NFS mount to a local drive on Martin's machine.

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The download began. Very slowly, but that was to be expected. (Note that nowadays you can download the latest Debian in about the time it takes to read this column, even on an average household connection. We've come a long long way.)

That was Monday afternoon. Monday night, it's still going. Tuesday morning it's not done yet, but Charlie can see data is trickling through, so leaves it alone.

Tuesday afternoon, there's a knock on the door. The departmental sysadmin and someone from the university network team are there, looking concerned.

"Which machine in here is called martin?"

"This one," replied Martin.

"Whatever you're doing on there, can you stop it? You're using up a quarter of the university's bandwidth."

Oops.

Remember what we mentioned before about how NFS had all sorts of neat tricks to restore dodgy connections? Well, funny story.

As Charlie puts it: "It turns out that running NFS, which has infinite retries over UDP, is not a particularly good idea over a long-distance network with reliability issues. The two machines end up screaming at each other as fast as they can: 'I CAN'T HEAR YOU!' 'WHAT DID YOU SAY?' 'I SAID I CAN'T HEAR YOU! SAY THAT AGAIN!' 'WHAT DID YOU SAY? THIS LINE IS TERRIBLE!'"

So not much of what was happening over that very chatty connection was Charlie's data.

The download was stopped, the sysadmins got their network back, and an important lesson was learned.

Also, Charlie found someone who already had the CD-ROMs for Debian and could post them to him. Those were the days.

Have you ever fixed one problem, only to create a whole other one no-one saw coming? Tell us all about it in an email to Who, Me? and we will make your exploits the stuff of legend. ®