From the VirtialBox User Manual i found this:"Delayed writing through the host OS cache is less secure. When the guest OS writes data,
it considers the data written even though it has not yet arrived on a physical disk". That may explain the missing files and wrong content.
But i still think vbox could warn end-users about that, on the "Settings->Storage"-section.

I mean , sometimes vbox warns about wrong chipset or dislay settings. It could say something about that caching thing too...

Maybe i'll try that "hostiocache off"-thing. Hopefully usb keeps working without problems... or i have to start to use GitHub or Dropbox or something.

It seems that i can make sqlalchemy fetch some data from tables when the connectionstrings are right.
But another thing i noticed, with a new vm, docker-compose can't find the .yml-file with -f. I have to say it's absolute path, then d-c finds it.
Any ideas why? And how to fix that? I ask here, in the case this is a Devuan-specific problem. (Almost 20 years there were some kind of a RedHat-related problem with package gcc, that other distros did'nt have.)

Something may have gone wrong with thet new vm's install. Or there is some important package missing. I noticed also that in the new vm's xfce terminal, there is no colours with output of "ls".

That's not weird when using root-account. But using a normal user account...

I guess i can forget to save file when tired enough. Or save under a wrong name. But 2 or 3 weeks of commits missing from git's log? Come on.

When i shut down a vm by clicking it's window's close button i get options to a) save machine state b) send shutdown signal c) send power off. Anything but a) could undo the changes.

But I usually shut down vm by saying sudo /sbin/shutdown or sudo /sbin/halt inside tah vm. So vbox should commit changes into the virtual hd.

Has Oracle changed vbox's behaviour concerning shutting down a vm , after 6.0 ? Or is it just a bug that reveals itself in the situation where the backing fs is almost full ?

For some reason i would like to mention another non-default-thing i did with virtualbox 5.x. I tried doing dd if=/dev/usb-disk or dd of=/dev/usb-disk and managed to froze the host machine so badly that i had to turn it off by pushing powerbutton.

With vbox 6.0 that usb-situation got little better. Don't remember freezing my machine with dd after that.

I always manage to try Things That Are Forbidden.

Maybe stackexchange.com would be a better place for this topic. But i don't have account on that site.

Anyways, changed logging settings in postgres-container. I started getting "LOG connection authetticated"-messages.
Entered into running python container with docker exec, started Python interpreter and started entering commands. Those "authenticated"-messages arrived into stderr. So now i know that sqlalchemy can connect into  postgres.

But "r=conn.execute(text("SELECT * FROM table1"))", which i tried instead of "c.select().where()" is still a problem. For some reason it doesn't return any rows. I think it should.
And it is very stupid if i have to enter commands that way.   I thought that with sqlalchemy, another way of doing queries would be possible.

https://www.youtube.com/watch?v=hJ-qU1nW0o0&t=0s Therion - Ginnungagap
not so much into Therion but this song sounds little like Bathory.

Beside the point. Haven't yet confirmed what happens if /mnt/vbox runs out of storage but i wouldn't trust the .vdi-files to propertly store my files on that situation either.

Speaking of "doing non-default-things with vbox", i have tried virtual machine files on usb harddrive and virtual machine files on samba share, with just a .vbox-file on /home. It was a bit difficult but kind of worked. The most recent version of vbox then was 5.something.

I think running some light software inside vm wouldn't cause problems. I mean not eating too much storage or ram or processor capacity.

But couple of months a go it seemed like a good idea to install Docker inside a vm instead of outside. The iptables rules that Docker insists on wouldn't interfere with the iptables rules i wrote. And problems with dns and Docker would go away also. (Dockerd sees only the dns server that vbox runs, not dnsmasq or anything like that.)
On the other hand, you can fill up your /var very fast by pulling all kinds of images and building containers.

Maybe the usb-problem is not fully vbox's fault. Recently bought a new usb-mouse and found out that the older one co-operates little better with Fujitsu.
I also run apt-get install and apt-get upgrade -u  recently, so some package may have broken usb somehow. On the other hand, problems with external mouse start after starting virtualbox.

I was hoping that i don't have to make backups or restore from hdd again. But i can do it if i really have to.
Btw, one thing i noticed:audio is not working. Tried some youtube videos and i can't hear a thing. Maybe it is just about volume, maybe about something else. Any ideas how to fix that?

Edit. found this:https://bbs.archlinux.org/viewtopic.php?id=265211 . I'll try that "options snd-intel-dspcfg dsp_driver=1"-thing soon.

Complaints about usb enumeration went away after upgrading the extpack. Tried the vm once, it was a bit slow to notice, but finally cat /proc/partitions showed /dev/disk/by-uuid/usb-stick.

Again, i wasn't precise enough with my previous message.

Not planning to make a mixture of new and old /.
The thing is:I don't want do destroy or format my /home-partition on Fujitsu. It will take some time to copy it back from hdd via usb.
I also need to keep the old / around long enough to copy some necessary files from /etc. Now i think that i got the contents for most of those files right, abt 4 months ago.
On the other hand, i think that configuration files i extracted from a memory stick are mostly unusable rotten crap.

Also root on lvm for new / would be nice but not absolutely necessary. Although no need to destroy previous vg containing /home for that.

So, bypassing the partitioning-part in installation process seems like a good idea.