@2000 Some or all of what I describe may have absolutely nothing to do with configuring Ubuntu 20.04 with BTRFSonLUKS but I thought I would run it by you in case this is something you have encoutered. If relevant I use an Samsung EVO 840 240GB and I followed all of Willi Mutschler’s guide including the part Step 3 (optional): Optimize mount options for SSD or NVME drives verbatim. I also use a swap file instead of a partition for hibernation which if I recall correctly is because when I looked into this it will allow me to later setup True hybrid-suspend/suspend-to-both/suspend-and-hibernate. I experience the same lockups on my Dell XPS 9360 although much less frequently and for less duration.
There are some logs here from early October when it was especially bad - again I have no reason to believe this is anything to do with BTRFSonLUKS rather than it just being some Ubuntu issue: 20.04.1 frequent freezes, hangs, or lockups?
On my desktop within a week or so after my setup I started experiencing regular lockups and system freezes that could occur perhaps 20 times per day, and I was thankfully able to resolve this in the past by rolling back with Timeshift Yesterday I downloaded ~10GiB of video and this morning I started receiving warnings about low disk space on root and after another reboot I could not get to the login screen. I dropped to a root recovery shell but apt clean and apt autoremove would not run as there was not enough space, ~64 KiB. I tried Bleachbit to free space, being sure not to select anything that mentioned backup files but it froze the system and I had to hard reset. I was able to roll back with Timeshift to a few days ago when I followed instructions I found to delete just the oldest kernel, which although has cleared ~60 GiB unfortunately seems to have removed all of my autosnapshots bar a manual one I took 19/09/20.
I have some HDDs I have not been using as I have been automounting as I have been trying to preserve their data before changing them from VeraCrypt (Desktop just froze for ~10 seconds) to LUKS, and I will get them set up as soon as I can so I can use for all downloads from now on but I wanted to ask if there is some better way I could handle Timeshift generally, how to free space if necessary in future without destroying backups, and if you have encountered anyone reporting similar freezes?