Tech bits

Two small tricks that I feel should be circulated more widely, because Google only disclosed them to me after a few false starts:

To figure out which processes are writing to the disk, I eventually found /proc/sys/vm/block_dump (see also chapter 5 of the Laptop Mode FAQ) which does exactly what I was hoping to find: it shows down to the level of process and file where disk writes are coming from. (Turns out, that kded and PowerDevil are currently appending to the .xsession-errors file regularly, keeping the disk busy on my new toy. Unlimited scrollback in konsole was the other culprit, but that one is switched off easily.)

Since I want to start backup on my netbook when it comes online at home, I figured the DHCP server was the likely place to trigger this. But the “execute” feature to start hook scripts on the DHCP server (see the dhcp-eval man page) was only added quite recently, so google first showed me a huge load of discussions involving tail on syslog and parsing its output. (I also found the simple event correlator which might be useful where “run command” features are not available.)