Wednesday, December 17, 2008

work that terminal award, command of the week

'Tis the season to be jolly, or jolly busy as we are in the waccy world of online retail.
In fact thats 99.99% of the reason i've been so quite recently.

But naturally, at this time of year, our thoughts turn to such questions as "how many MaxClients should I have?" and "are keepalives better or worse for overall performance?" but the question exercising our minds today has been "what *are* all those ip_conntrack entries?".

Rewind a little... a) I turned keepalives off, and reduced MaxClients, things seemed to be more controlled without all those idle processes ready to receive requests with no warning.
b) We'd always had a low but persistent number of "can't connect", or "no html" errors reported by external beacons, and when we applied test loads this went through the roof.

So today, dmesg says.. ip_conntrack: table full, dropping packet.

Which brings me to the point of this post, we increased the size of the table in line with the unverified facts, lies, and dodgy misinformation prevelant on the web ;-)

That helped, but now we want to know whats in the ip_conntrack?

Enter the victor of the command of the week award..

grep ^tcp /proc/net/ip_conntrack | awk '{print $4}' | sort | uniq -c

Whos output turns a whole mess of gobbledy gook into something like this:


Knowedge is power, have an award Patrick Schaaf. :-)


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I know nothing, I'm not a fortune teller, and you'd be insane to think that I am. This disclaimer was cribbed from an email footer I once received. It is so ridiculous I had to have it for myself.

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