For a while now, we’ve been waiting for a relatively easy method of creating bit-replica UBIFS images of the internal N900 rootfs. Some methods involved creating a quasi dual-boot system booting a Mer or Debian system and then `dd`ing the entire 256MB NAND chip and others simply ran a primitive rsync to backup. Now with BackupMenu (based on RescueMenu) it’s a fairly straight forward process.
The only dependency is bootmenu which patches initfs and allows off-chip boot capabilities. To install BackupMenu, simply enable Extras-Devel and issue `apt-get install backupmenu`. A simple file will be dropped into /etc/bootmenu.d/. You have access to USB Networking with an SSHd, Backup/Restore of RootFS and OptFS (/opt/) a semi-functional busybox shell as well as access to internal 32GB and any microSD card.
If you tinker with your N900 and have a lot of internal filesystem customizations, this is a very valuable tool for creating instant copies of your device for restoration and archival purposes.