A few days in Edinburgh

I have been working with the MIS people at Edinburgh University and a consultant from Tribal which has been much fun indeed. I learned a number of things and was reminded of a few more my brain have choosen to put in long term storage.

  • cron starts non-root processes with a NICE value of 2 hence will have a lower priority than jobs started on the command line or via SMF. The queuedefs man page explains more, but the syntax is arcane!
  • Worth snooping traffic to and from the DNS server. Often shows up errors or performance opportunities in nscd.conf and resolve.conf such as having cache-enable set to no for ipnodes.
  • If any type of network latency is important such as in ping-pong of packets sitting on 2 clients, map out and understand where your firewall(s) sit(s) and benchmark without the firewall to get the scope of the impact. Firewalls are often an invisible(and hard to observe) component, so are often ignored.
  • Turning TCP NAGLE off via ndd is well worthwhile if ping-pong latency is a barrier.

Next race is on Saturday which is the Snowdon International Race.

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