Rootfs

Rootfs is the filesystem that the root directory is on. The N900 has a 256M OneNAND chip that's used for rootfs, bootloader and kernel and a (slower) 32GB eMMC flash that's partitioned for 768M swap space, 2G /home, and 27G /home/user/MyDocs. Due to the fact that the 256MB chip is faster (better connected to the processor, perhaps) every application installs a bit of itself in rootfs, some more than others, and the rest of it they install on other parts of the device. Applications that have been designed to install as little of themselves as they can are referred to as "optified". For being so small rootfs tends to run out real quick, so one must be aware of it, a good way to keep track is to download Conky (or the desktop command widget) and check it out once in a while. If you run out of space, you can't install anything else.. Firmware updates require huge amounts of rootfs space (Just for installation) and updating can become extremely problematic. You can find ways to free up rootfs in this wiki page: http://wiki.maemo.org/Free_up_rootfs_space