diff --git a/client/operation.go b/client/operation.go
index dcf04c7..21c482f 100644
--- a/client/operation.go
+++ b/client/operation.go
@@ -192,7 +192,7 @@ func prepareProcessLaunch(storageRoot string, req *shared.StartProcessRequest) *
 	return nil
 }
 
-func makeLogFile(meta *procmeta, idx int) string {
+func makeLogFilePrefix(meta *procmeta) string {
 	now := time.Now().UTC()
 	ext := path.Ext(meta.args[0])
 	nameonly := path.Base(meta.args[0])
@@ -200,8 +200,7 @@ func makeLogFile(meta *procmeta, idx int) string {
 		nameonly = nameonly[:len(nameonly)-len(ext)]
 	}
 	ts := now.Format("2006-01-02T15-04-05")
-	stdPrefix := path.Join(meta.cmd.Dir, "logs", fmt.Sprintf("%s_%s", nameonly, ts))
-	return fmt.Sprintf("%s_%d.log", stdPrefix, idx)
+	return path.Join(meta.cmd.Dir, "logs", fmt.Sprintf("%s_%s", nameonly, ts))
 }
 
 func (hc *houstonClient) launch(meta *procmeta) error {
@@ -209,10 +208,6 @@ func (hc *houstonClient) launch(meta *procmeta) error {
 	if err != nil {
 		return err
 	}
-	stderr, err := meta.cmd.StderrPipe()
-	if err != nil {
-		return err
-	}
 
 	err = os.MkdirAll(path.Join(meta.cmd.Dir, "logs"), 0775)
 	if err != nil {
@@ -233,7 +228,8 @@ func (hc *houstonClient) launch(meta *procmeta) error {
 		thisFileSize := 0
 		logFileIndex := 0
 
-		logFileName := makeLogFile(meta, logFileIndex)
+		logFileNamePrefix := makeLogFilePrefix(meta)
+		logFileName := fmt.Sprintf("%s_%d.log", logFileNamePrefix, logFileIndex)
 		targetFile, err := os.Create(logFileName)
 		if err != nil {
 			logger.Println("failed to create log file :", logFileName)
@@ -241,7 +237,10 @@ func (hc *houstonClient) launch(meta *procmeta) error {
 		}
 
 		exef, _ := os.Executable()
-		os.Symlink(path.Base(targetFile.Name()), path.Join(path.Dir(exef), path.Dir(logFileName), meta.name+".log"))
+		linkePath := path.Join(path.Dir(exef), path.Dir(logFileName), meta.name+".log")
+
+		os.Remove(linkePath)
+		os.Symlink(path.Base(targetFile.Name()), linkePath)
 
 		defer func() {
 			if targetFile != nil {
@@ -266,23 +265,23 @@ func (hc *houstonClient) launch(meta *procmeta) error {
 				}
 			}
 
-			if thisFileSize > 10*1024*1024 {
+			if thisFileSize > 5*1024*1024 {
 				logFileIndex++
-				logFileName := makeLogFile(meta, logFileIndex)
+				logFileName = fmt.Sprintf("%s_%d.log", logFileNamePrefix, logFileIndex)
 				nextTargetFile, err := os.Create(logFileName)
 				if err != nil {
 					logger.Println("failed to create log file :", logFileName)
 				} else {
 					targetFile.Close()
 					targetFile = nextTargetFile
-					os.Symlink(path.Base(targetFile.Name()), path.Join(path.Dir(exef), path.Dir(logFileName), meta.name+".log"))
+					os.Remove(linkePath)
+					os.Symlink(path.Base(targetFile.Name()), linkePath)
 					thisFileSize = 0
 				}
 			}
 		}
 	}
 
-	go stdReader(stderr)
 	go stdReader(stdout)
 
 	logger.Println("startChildProcess :", meta.cmd.Args)