This new commanline option for the cmk tool will change exising RRD databases to match the configuration that is done via the WATO rulesets Configuration of RRD databases of hosts and Configuration of RRD databases of services. Otherwise changes in these rules applied only on new RRDs.
You can restrict the conversion to one or several hosts:
OMD[mysite]:~$ cmk -v --convert-rrds myhost1 myhost2 myhost1: HOST - rta....uptodate - pl....uptodate - rtmax....uptodate - rtmin....uptodate Postfix Queue - length....uptodate - size....uptodate CPU utilization - user....converted, 376 KB -> 40 KB - system....converted, 376 KB -> 40 KB - wait....converted, 376 KB -> 40 KB [...]
If you do not specify any hostname, then all RRDs will be converted.
Note: this new option uses a completely new feature of the RRDTool, which has been sponsored by Mathias Kettner: RRDTool can now change the internal structure of RRDs on-the-fly. That way it is now for example possible to change the range of time or precision that data is being kept.
Note 2: this feature uses an experimental version of RRDTool. Please make a backup of your RRDs before trying this out.