I have a 32GB, USB 2.0 ICIDU USB stick that I want to connect to my Raspi for storing ownCloud files. The stick is FAT32 formatted, from factory. My Raspi is running ownCloud 6 using this image: http://www.owncloudbook.com/owncloud-on-raspberry-pi/
When connecting the stick it gets very warm/hot after only 1 or 2 minutes (just sitting idle). Unfortunately the stick doesn't have an activity light; I can't see if my Raspi is doing anything to it. I've hooked up a simple power measuring device and the Raspi consumes 370mA on its own and jumps to 470mA with the USB stick. When the stick is connected to my Windows PC it draws about 90mA, but it does not turn warm, not even a little bit.
So the question is: what could cause the stick to warm up when connected to the Raspi, and what can I do to prevent it?
UPDATE The stick also gets hot when connected to a Windows PC while files are being copied. It is safe to assume read/write actions cause the stick to heat up. Power consumption rises from 90mA to 140mA during active periods.
I previously had the stick mounted as /var/www to store ownCloud files on it. Mounting the stick in /media/usbstick doesn't cause heat. Somehow Apache2 seems to cause constant read/write activity when the stick is mounted in /var/www
UPDATE 2 Here's what I did to keep temperature down :)
The heat sink comes from an old 7805 voltage stabilizer. Surprisingly, it fits exactly. The stick has an aluminium casing, which helps with heat dissipation.