set file=$system.Util.ManagerDirectory()_"messages.log"
open file:("RS"):1 w $T  open 2:99
try { for n=1:1 use file read lin use 2 write lin,! } catch { close 2,file  write n_" lines",! }

then use ^SPOOL mapping (OEX) to work on it with SQL

Hello Hannes!
Thanks for the hint ! I'll check immedeatly.
-  for the stop:
I've seen this in some cases but could imagine it related to large global buffers.
default timeout for docker stop iris is 10 sec  but  docker stop -t 60  iris will give it a minute
the total save approach could be 
docker exec iris iris stop iris quietly      so iris is down
docker stop iris                                          now stop the container