home backup files vanish

[alcina]

Software
XBian version: 1.0 Knockout
XBMC/Kodi version: 18.5 (also a problem when it was 18.3)
Overclock settings: default


Hardware
Device type and model: RPi3B
Power supply rating: 3A
SD card size and make/type: 64G SanDisk SDXC UHS-I (also a problem with 16G SanDisk)
Network (Ethernet or wireless): ethernet
Connected devices: TV, NAS (Netgear) via nfs

Problem description:
The backups of /home disappear the moment they are completed. The backups of system are fine.

In xbian-config I have it set to backup home every day and the system weekly. I have only set this up recently, mostly because I figure I should In the past I have manually rsynced files or done an image of the SD card to back up. It is set to backup to a folder on the NAS. xbian has write permissions to this NAS. The system backup happens and there is the image file. It is about 8.5G. But when I looked there were never any home backups. Using the GUI I told it to backup home 'now'. It started the backup, I checked the NAS and could see the home img.gz file getting bigger and bigger until it got to the approximate size of the xbian home directory - about 6G. Then it disappeared. The log file says:

Code:

2021-04-15 15:08:52.716 T:2063569632   DEBUG: XBian-config : xbian-config xbiancopy homestatus : ['0']
2021-04-15 15:28:59.353 T:2398089952   DEBUG: Previous line repeats 356 times.
2021-04-15 15:28:59.404 T:2398089952   DEBUG: <Event dir=True mask=0x40000200 maskname=IN_DELETE|IN_ISDIR name=xbian-storage path=/run pathname=/run/xbian-storage wd=2 >
2021-04-15 15:28:59.405 T:2063569632   DEBUG: XBian-config : xbian-config xbiancopy homestatus : ['-1']
2021-04-15 15:29:02.409 T:2063569632   DEBUG: getSetting file: /home/xbian/.kodi/userdata/addon_data/plugin.xbianconfig/notifyonerror=1
2021-04-15 15:29:02.431 T:2985345888   DEBUG: ------ Window Init (DialogNotification.xml) ------
2021-04-15 15:29:02.432 T:2985345888   DEBUG: Window DialogNotification.xml was already loaded
2021-04-15 15:29:02.432 T:2985345888   DEBUG: Alloc resources: 0.02ms
2021-04-15 15:29:18.186 T:2985345888   DEBUG: ------ Window Deinit (DialogNotification.xml) ------

At the point the WindowDialogNotification bit happened, the GUI on the tv flashed a notice which said "Can't prepare destination file.." or it might have been "Can't prepare destination files" - it didn't seem to fit the screen and then it disappeared off the screen.

I then used the commandline GUI and selected to backup the home directory to /xbian-backup/temp (so the local SD drive, in case it was a NAS/network issue). Again I watched the file get bigger until it reached the approximate size of the home directory, then the GUI said: "Backup /home process failed!" and the file that had been in /xbian-backup/temp disappeared. This time there was nothing at all in the log file.

Background: This was also happening before I upgraded from 18.3 to 18.5 - I was hoping the upgrade would fix it. My main problem at the time though was the memory leak, for which the answer was "it's been fixed, upgrade!". At the time of upgrading I also changed to a bigger 64G SD card (thank you Nachteule for the excellent instructions on how to do this if it doesn't expand automatically) as I thought that perhaps it was simply running out of space on the card. When I just said "upgrade everything" the Pi would hang on the "network started" screen and get no further. So I would roll back to the previous btrfs (again thank you Nachteule for the clear instructions on how to do this, I am LOVING btrfs!) and try again. Eventually I decided to upgrade the Debian bits, rebooting between almost each one, then when they were all installed I started on upgrading the xbian bits one by one, trying to do them in chronological order. I managed to install all of them except xbian-upgrade. Each time on the reboot it would do the mercury coming together splash screen, then drop into commandline login before reaching the Kodi splash screen. The log file indicated missing python modules ("builtins", then then next time "pyinotify"). I installed those but it is still crashing out into commandline login at boot time. So I haven't installed xbian-upgrade yet. This may be a completely different issue, but I thought I'm mention it in case it is relevant!


How to reproduce:
Try to backup the home directory using the inbuilt tools.