by Ken Task.
Too bad about removing the old CID 1 backups ... was going to suggest gunzipping them to see how large the .xml files were - in particular, the users.xml. That's something I've not asked and you've not provided .... how many users on the system? Also, what roles do you have assigned to the front page ... after successful login? What activities/blocks do you have showing on the front page *after* login?
How many courses does site have?
Anything in moodledata/temp/backup/ is temporary and used for a build area for backups. Safe to remove anything in moodledata/temp/backup/. The temp directories in there should never conflict with other temp directories used to build a course - CID 1 would never get the same contenthashed named directory (if that's what were thinking). If there is anything in moodledata/temp/backup/ delete it. Next run of autobackups then, the only thing that should remain is all the course backups that failed - and according to what you've shared, the table shows only course ID 1 is unfinished so what remains in moodledata/temp/backup/ should be the front page.
You're on Linux ... so start the automated backup script in /admin/cli/ from command line in an ssh shell. Open another terminal Course ID 1 would be first to backup. In the second terminal session, cd /path/to/moodledata/temp/backup/
ls -l
Should see the contenthashed directory created for the backup build ... long folder name ....
cd [thatlongfoldername]
Then:
watch "ls -lR"
and you can watch the build of the backup in *realtime*.
Your terminal session running the autobackup script will need to be left running and allowed to terminate it's own session (shouldn't kill the process, however).
As far as moodle retaining what contenthash named directory it was using to build a backup in some temp table ... uhhhhh, why? If a backup fails, the directory will be there and thought it's name was the contenthash at the time.
What is so important about those tables related to autobackups that you do not want to truncate them? Think at this point, I'd go with what worked on dev.
And just so you are clear ... you do know that CID 1 (the front page) cannot restored to the front page of a Moodle site, right?
At this point .... have suggested all I can think of .... best of luck.
'spirit of sharing', Ken