I'm new to Android system. I'm trying to understand how it is installed to internal memory to eventually have it fully backed up and capable to be restored. To accomplish it I need to know what to back up. Is /data & /system partitions all I have to care of? One of my root apps list these partitions on my device:

/mnt/media_rw/xxxx-xxxx (mounted external SD card, Idk how to treat it)
/data 5.51GB
/system 1.08GB
/cache 534.12MB
/fsg 1.5MB
/firmware 64MB
/persist 8MB
/pds 3MB
  1. What is the full list of physical partitions on Android device?
  2. Can the list differ between devices?
  3. TWRP, Titanium, oandbackup and (adb backub/restore) do not create full backups of Android device (system with data). What is a complete solution on Android devices similar to Acronis True Image on PC systems?

The list certainly differs between devices, and thus no exhaustive list can be provided.

For most if not all devices, there is no need to backup partitions other than system (system), data (user data), boot (kernel) and vendor (for Treble devices, a separate vendor stores hardware drivers, etc.).

Many of those extra partitions are not user-accessible and/or store data for non-OS components (e.g. modem for baseband, logo for 1st splash logo on boot), and no procedure would touch them in daily use other than system updates. On top of that, without root access you will not be able to perform full backup/restore even on data.

Currently the common way of doing a full-enough backup is just backing up the ones listed in the backup menu from TWRP, which already covers more than just "system with data" as you required. Depending on the maintainer/builder of the TWRP in use, other partitions might also be available for backup/restore, though for the reason above there's no point in doing so (and is why most TWRP builds choose to hide them).

  • I'm afraid TWRP backup excludes /data/media, thus it is not full data backup. twrp.me/faq/backupexclusions.html – kagetoki Jul 27 '18 at 0:01
  • True, I guess as seasoned ROM flashers we tend to just take "data" as /data. What prevents you from just copying it out though? – Andy Yan Jul 27 '18 at 0:04
  • I thought about simple e.g. "adb copy/paste (/system, /data) /path" command. I don't know if it would be achievable, though. I'm not familiar with adb and its reliability. Someone, give me complete instructions and specific adb commands to perform copy/overwrite, please. I bet there will be a hundred obstacles. – kagetoki Jul 27 '18 at 0:31
  • It'd be some serious loophole if it were as easy as that. Closest I know is using dd to dump/write individual partitions, but I remember seeing some examples that using this doesn't always work (might result in bricked device). Besides, this doesn't help with backing up internal storage either. – Andy Yan Jul 27 '18 at 11:35

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