Backup Dos

How to save space before you back up

Clear trash and caches
1. at ~/.cache/chromium/Default
2. at ~/.ros
3. 'pip3 cache purge'
4. Lastly, at ~/.local/share/Trash/expunged/*
To check large files and directories
sudo du -Sh | sort -rh | head -20
To clear unallocated disk space to zero, use zerofree utility (apt install)
1. boot into single user mode sudo init 1 (init level 3 may not work. If no keyboard response, try switch to init 3 first and then into init 1 state, after a fresh reboot)
2. remount the filesystem to readonly (if failed, reboot the system and try again) mount -o remount,ro /dev/mmcblk0p1
  - If the mounting is busy try stop services as followed
  - killall dhclient (this should make things work already)
  - systemctl stop rsyslog
  - systemctl stop network-manager
  - if still, run systemctl status to identify further things to stop
3. perform zerofree command zerofree -v /dev/mmcblk0p1
4. regarding the meaning of the zerofree output:
  So after some detailed analysis it would look like those numbers are as follows:
  - number of nonzero blocks encountered
  - number of free blocks within the filesystem
  - total number of blocks within the filesystem
5. poweroff and start backup in recovery mode

In the Linux_for_Tegra/ folder, perform backup of the APP partition

sudo XZ_OPT=-T0 tar -Jcvf xxx.tar.xz Linux_for_Tegra

sudo is used to be able to access all files
-T0 is to enable multi-threading (tar -Jcvf file.tar.xz /path is too slow, as it is single threaded)