I'm trying to get rrdtool to work under collectd. When I first tried, rrdtool gave a mmap error when it tried to update its datafile. I read a post in the Forum that said the JFFS2 file system doesn't support mmap(), so I moved the data file to tmpfs just like debian does with the apt cache for the same reason. That eliminated the mmap error, but has the unfortunate side effect that the datafile will disappear on reboot.
Does anyone have any suggestions about somewhere else to put the data file that will work with mmap but will survive a reboot?