Actually I think he was referring to the BackupMenu application available in the repositories - NOT the Backup app that comes with the N900.

http://maemo.org/packages/view/backupmenu/

BackupMenu allows you to create a complete image backup (rootfs + optfs) of the entire system which can then be reflashed at any point using the flasher tool.

-DJ

Is there someone who has succesfully gained direct access to eMMC disk via USB mass storage and R&D? Enabling the latter was easy, but I keep getting the message that there is no media in the removable drive (both, eMMC and microSD). This cannot be about the partition going unrecognized. If I power on the device then I can access the VFAT partition but not the whole disk. I will have to go with BackupMenu if this does not work otherwise.

Update: I now had great success. Meego Wiki has instructions how to boot N900 to initrd rescue environment without doing anything to the device itself (it's one-shot boot using only RAM). I turned USB access on there and imaged the device using Acronis TrueImage Echo. Just what I wanted.

BackupMenu is by far easier to use than rsync over the network, if you are not very familiar with all the options it has. Syncing a running system is said to be a bad idea, because too much is not syncable.
Syncing the possible directories takes much more time than BackupMenu with its minimal shell.

My 2 cents: The way you are expecting the 'ghost'-ing of the N900 to work is far to complicated compared to the available solution