Thursday, 22 October 2015

TWRP Nandroid backups of /data won't restore



None of my /data backups from the past month will restore. Instead, each restore will end with "extractTarFork() process ended with ERROR=255" (more from log below).

Code:


file: //data/data/com.android.externalstorage/lib
  ==> extracting: //data/data/com.android.externalstorage/lib (symlink to )
symlink(): No such file or directory
FAILED RESTORE OF FILE i: //data/data/com.android.externalstorage/lib
E:Unable to extract tar archive '/data/media/0/TWRP/BACKUPS/04ce21cdcfd6c9c3/2015-10-22--16-35-10/data.f2fs.win000'
I:Error extracting '/data/media/0/TWRP/BACKUPS/04ce21cdcfd6c9c3/2015-10-22--16-35-10/data.f2fs.win000' in thread ID 0
E:Error extracting split archive.
E:extractTarFork() process ended with ERROR=255


Here's the setup:
Recovery: Multirom TWRP (2015-06-30 2.8.7)
ROM: CM12.1 nightlies and more recently crDroid (CM12.1 based)
F2FS formatted /data, /cache, /sdcard

Here's what I've done to investigate:
1. Thinking the problem had to do with compressed backups, I uncompressed using Nandroid Manager. No difference.
2. Thinking the problem had to do with the backup being spread across multiple .win tar files, I concatenated them into one .win tar file. No difference.
3. Thinking that perhaps I could unarchive the tar and adb push the /data partition. It pushed fine and booted, however the davlik cache wasn't rebuilt when booting and the OS was unusable due to FC.
4. Thinking that I just needed to remove the files/directories that were throwing errors during restore, I used tar --delete to remove files/directory from the nandroid backup. This was somewhat successful in that the restore would progress further before failing, but it would just throw a similar error for another directory.

I haven't figured out why these backups won't restore, but I've thus far resorted to just restoring my most recent backup that will restore. The problem with this is that my future backups seem to have this same problem of not being restorable.

What to do?



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