diff --git a/app/Main.hs b/app/Main.hs
index c08cd3c..80c0520 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -54,8 +54,8 @@ readConfig = do
             bootstrapHost : bootstrapPortString : _ ->
                 [(bootstrapHost, read bootstrapPortString)]
             _ -> []
-        fConf = FediChordConf {
-            confDomain = confDomainString
+        fConf = FediChordConf
+          { confDomain = confDomainString
           , confIP = toHostAddress6 . read $ ipString
           , confDhtPort = read portString
           , confBootstrapNodes = confBootstrapNodes'
@@ -67,11 +67,12 @@ readConfig = do
           , confResponsePurgeAge = 60 / fromIntegral speedup
           , confRequestTimeout = 5 * 10^6 `div` speedup
           , confRequestRetries = 3
-                           }
-        sConf = ServiceConf {
-            confSubscriptionExpiryTime = fromIntegral $ 2*3600 `div` speedup
+          }
+        sConf = ServiceConf
+          { confSubscriptionExpiryTime = fromIntegral $ 2*3600 `div` speedup
           , confServicePort = read servicePortString
           , confServiceHost = confDomainString
-                            }
+          , confLogfilePath = "../simulationData/logs/" <> confDomainString <> ".log"
+          }
     pure (fConf, sConf)
 
diff --git a/src/Hash2Pub/FediChordTypes.hs b/src/Hash2Pub/FediChordTypes.hs
index 3b563e6..725031e 100644
--- a/src/Hash2Pub/FediChordTypes.hs
+++ b/src/Hash2Pub/FediChordTypes.hs
@@ -457,6 +457,8 @@ data ServiceConf = ServiceConf
     -- ^ listening port for service
     , confServiceHost            :: String
     -- ^ hostname of service
+    , confLogfilePath            :: String
+    -- ^ where to store the (measurement) log file
     }
 
 class DHT d where
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index c556d7f..2abf3b8 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -25,6 +25,7 @@ import           Data.Maybe                (fromJust, isJust)
 import           Data.String               (fromString)
 import           Data.Text.Lazy            (Text)
 import qualified Data.Text.Lazy            as Txt
+import qualified Data.Text.Lazy.IO         as TxtI
 import           Data.Text.Normalize       (NormalizationMode (NFC), normalize)
 import           Data.Time.Clock.POSIX
 import           Data.Typeable             (Typeable)
@@ -109,6 +110,8 @@ instance DHT d => Service PostService d where
               }
             port' = fromIntegral (confServicePort conf)
             warpSettings = Warp.setPort port' . Warp.setHost (fromString . confServiceHost $ conf) $ Warp.defaultSettings
+        -- log a start message, this also truncates existing files
+        TxtI.writeFile (confLogfilePath conf) "# Starting mock relay implementation\n"
         -- Run 'concurrently_' from another thread to be able to return the
         -- 'PostService'.
         -- Terminating that parent thread will make all child threads terminate as well.
@@ -745,10 +748,18 @@ evaluateStatsThread serv statsAcc = getPOSIXTime >>= loop
           -- be read afterwards
           now <- getPOSIXTime
           -- evaluate stats rate and replace server stats
-          atomically . writeTVar (loadStats serv) . evaluateStats (now - previousTs) $ summedStats
-          -- idea: let another thread periodically exchange the RelayStats, modify it atomically (Konzept "unterm Arsch wegziehen")
-          -- and now what? write a log to file, probably as a forkIO
           -- persistently store in a TVar so it can be retrieved later by the DHT
+          atomically . writeTVar (loadStats serv) . evaluateStats (now - previousTs) $ summedStats
+          -- and now what? write a log to file
+          -- format: total relayReceiveRates;total relayDeliveryRates;postFetchRate;postPublishRate
+          -- later: current (reported) load, target load
+          TxtI.appendFile (confLogfilePath . serviceConf $ serv) $
+              Txt.intercalate ";" (Txt.pack <$> (
+              [ show . sum . relayReceiveRates
+              , show . sum . relayDeliveryRates
+              , show . postPublishRate
+              , show . postFetchRate
+              ] <*> pure summedStats)) <> "\n"
           loop now