And on top of all that USB, RAID, and LUKS, you’re using btrfs.
It could be that some of btrfs’s features are causing you serious problems.
No, btrfs isn’t a bad file system at all, and it has some fascinating features. But the combination you’ve set up is practically begging for trouble.
Btrfs is a journaling filesystem. This means, among other things, that it has to perform cleanup more often than other filesystems. When it does this, it has to read, analyze, and rewrite entire chunks (1GB). Combined with USB, LUKS, and USB RAID, this means a lot of work for the filesystem.
This process is more efficient the less full the filesystem is.
It wouldn’t be unusual for long pauses to occur in your setup during emergencies.
Please check the current status of your filesystem using btrfs usage (and show it here).
sudo btrfs filesystem usage /
You find good Information about Btrfs in the wiki (<- link)
noatime
Ensure all btrfs volumes are mounted with noatime as an option.
why?
This makes btrfs faster and avoids generating unnecessary metadata when files are only read. Details are linked at:
make btrfs faster
A proper swap partition can be a real help in this situation.
But not in your case, it’s located on the same device and is also encrypted. What’s intended as a relief therefore becomes an additional burden in this configuration.
