Node "to" looks to have had an internal power/cooling failure and seems to have shut itself down at 20:15. It looks as the tre node has also shut itself down (at 20:35) to avoid filesystem corruption with the crash of to.
23:55: all nodes up again
Technical note: tre had a problem when it was booted again that it blocked itself out from the rest (HACMP problem). After the other nodes where rebooted and up again. It was possible to start the hacmp service on tre again.