|Swappiness: note that swap = 0 (htop).|
Noted that the swap disk often was active. But the system had sufficient RAM. Research suggested, that the swappiness should change to 10. Tried it, and now the system seems to behave as I want i to.
- 0 => only use swap if all RAM is used.
- 10 => use swap if needed if around 80 - 90% of the RAM is used.
- 100 => swap is on always.
100 may be a solution on old systems, if you cannot upgrade RAM the swap can save the day. Whether this is heathy for the harddisk, I don't know.