Disk chatter every 5 seconds

[Daniel Allen]

Ubuntu (5.04 and 5.10) seem to run a device-related daemon (HALd?
udev?) which makes the disk activate in a short burst exactly every 5
seconds.  Since the disk is the loudest part of my home system, the
pattern is sometimes a bit distracting.

Anybody know what's the cause, and whether it's configurable behavior?
 I have done a bit of poking, but I haven't been able to isolate it,
beyond that it doesn't happen in runlevel 2, and it doesn't stay
active long enough to show up in 'top'.

Thanks for any help,

-Daniel