document important log files i found out about in ganeti

howto/ganeti.md

@@ -2255,8 +2255,15 @@ Ganeti has of course its own [issue tracker on GitHub](https://github.com/ganeti
 
 ## Logs and metrics
 
-<!-- TODO: where are the logs? how long are they kept? any PII? -->
-<!-- what about performance metrics? same questions -->
+Ganeti logs a significant amount of information in
+`/var/log/ganeti.log`. Those logs are of particular interest:
+
+ * `node-daemon.log`: all low-level commands and HTTP requests on the
+   node daemon, includes, for example, LVM and DRBD commands
+ * `os/*$hostname*.log`: installation log for machine `$hostname`
+
+It does not expose performance metrics that are digested by Prometheus
+right now, but that would be an interesting feature to add.
 
 ## Other documentation