hardware

...so he tries to get too frickin' clever..

Michael Fleming

Jan 4, 2007 • 2 min read

…and almost loses.

As noted in my last entry, I picked up a gigabit switch in the post Christmas sales along with a suitable network card. Today, being a generally wet/overcast day (meaning “watch cricket on the TV and hack around a bit if it’s slow”) I picked up a matching gig card for Qbert, my server.
For someone of my experience, this installation would not normally pose an issue. Alas, as it’s my homebrew FrankenServer and not one of the nicer pre-built IBM/HP jobs I deal with at work, I obtained the following wisdom (or thoroughly LARTed, depending on your perspective).

While all sentient beings have Buddha-nature, can become bodhisattvas and save others from suffering, all non-sentient computer hardware has Bastard-nature, can become mischievous and cause great suffering.

The card slotted in fine, everything powered up ok initially – except it decided to throw a watchdog error and refuse to pass traffic. A reboot, reconfigure – nothing. Frob a couple of extra bits in BIOS. Nope – what NIC are you talking about, thinks the system. A regression / sense of deja-vu tells me to try another PCI slot and take the IRQ away from the USB ports (which Linux will handle OK thanks)… Bingo.

“I want to transfer packets,

But the switch I cannot see,

A power cycles helps not,

Fscking IRQ conflicts!”

Well – all was OK. I’ve not seen an IRQ conflict in years – even on old, decrepit crap (like pong). Seems the RAID array controller and the new NIC wanted the same thing, as the others had already been taken according to BIOS. Removing the USB IRQs freed enough for them to go their seperate ways.

This leads me to a second oddity, but less of a problem for my situation. It seems the new switch (a Linksys SD2008 for those interested – 8 port unmanaged switch) doesn’t support jumbo frames.

What’s a jumbo frame you ask? Gigabit ethernet supports frames with a Maximum Transfer Unit (MTU) larger than the normal Ethernet standard of 1500 bytes – often up to 9216bytes per frame. This is very handy for huge files (video, CAD documents, massive images). However this switch lacks the capability according to some Googling.

Mind you, the testing I’ve performed gives me quite adequate transfer rates (around 2G a minute plus) so I’m not overly concerned. I’m primarily interested in spooling smaller files from my server (mail, RPMs for build systems, music and SMB/NFS shared files) than massive images. Still, how many places will sell an 8 port gig switch for $AU150 (without it being shite)?

I’ll see how it all fares in the longer term ?

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