diff --git a/log.go b/log.go
index 7c06cd7..9525d6e 100644
--- a/log.go
+++ b/log.go
@@ -19,7 +19,7 @@ import (
 type Log struct {
 	ApplyFunc   func(Command) error
 	file        *os.File
-	path		string
+	path        string
 	entries     []*LogEntry
 	commitIndex uint64
 	mutex       sync.Mutex
@@ -412,7 +412,7 @@ func (l *Log) appendEntry(entry *LogEntry) error {
 //--------------------------------------
 
 // compaction the log before index
-func (l *Log) Compaction(index uint64, term uint64) error {
+func (l *Log) Compact(index uint64, term uint64) error {
 	var entries []*LogEntry
 
 	l.mutex.Lock()
@@ -444,9 +444,16 @@ func (l *Log) Compaction(index uint64, term uint64) error {
 	l.file.Close()
 
 	// remove the current log file to .bak
-	os.Remove(l.path)
+	err = os.Remove(l.path)
+	if err != nil {
+		return err
+	}
+
 	// rename the new log file
-	os.Rename(l.path + ".new", l.path)
+	err = os.Rename(l.path + ".new", l.path)
+	if err != nil {
+		return err
+	}
 	l.file = file
 
 	// compaction the in memory log
diff --git a/peer.go b/peer.go
index 1901965..ab12744 100644
--- a/peer.go
+++ b/peer.go
@@ -213,27 +213,30 @@ func (p *Peer) heartbeatTimeoutFunc(startChannel chan bool) {
 			p.mutex.Lock()
 			server, prevLogIndex := p.server, p.prevLogIndex
 			p.mutex.Unlock()
-			
+	
+			var req *AppendEntriesRequest
+			snapShotNeeded := false
+
+			// we need to hold the log lock to create AppendEntriesRequest
+			// avoid snapshot to delete the desired entries before AEQ()
 			server.log.mutex.Lock()
-			if prevLogIndex < server.log.StartIndex() {
+			if prevLogIndex >= server.log.StartIndex() {
+				req = server.createAppendEntriesRequest(prevLogIndex)
+			} else {
+				snapShotNeeded = true
+			}
+			server.log.mutex.Unlock()
 
-				// request the log before the latest snapshot
-				// send out the snapshot
-				server.log.mutex.Unlock()
+			p.mutex.Lock()
+			if snapShotNeeded {
 				req := server.createSnapshotRequest()
-
-				p.mutex.Lock()
 				p.sendSnapshotRequest(req)
-				p.mutex.Unlock()
 			} else {
-
-				// Lock the server to create a request.
-				req := server.createAppendEntriesRequest(prevLogIndex)
-				server.log.mutex.Unlock()
-				p.mutex.Lock()
 				p.sendFlushRequest(req)
-				p.mutex.Unlock()
 			}
+			p.mutex.Unlock()
+
+
 		} else {
 			break
 		}
diff --git a/server.go b/server.go
index 4fac4ff..40b2afc 100644
--- a/server.go
+++ b/server.go
@@ -8,6 +8,7 @@ import (
 	"os"
 	"sort"
 	"bufio"
+	"path"
 )
 
 //------------------------------------------------------------------------------
@@ -791,7 +792,7 @@ func (s *Server) takeSnapshot() error {
 
 	s.saveSnapshot()
 
-	s.log.Compaction(lastIndex, lastTerm)
+	s.log.Compact(lastIndex, lastTerm)
 
 	return nil
 }
@@ -822,7 +823,7 @@ func (s *Server) saveSnapshot() error {
 
 // Retrieves the log path for the server.
 func (s *Server) SnapshotPath(lastIndex uint64, lastTerm uint64) string {
-	return fmt.Sprintf("%s/snapshot/%v_%v.ss", s.path, lastTerm, lastIndex)
+	return path.Join(s.path, "snapshot", fmt.Sprintf("%v_%v.ss", lastTerm, lastIndex))
 }
 
 
@@ -840,7 +841,7 @@ func (s *Server) SnapshotRecovery(index uint64, term uint64, machineState int) (
 	snapshotPath := s.SnapshotPath(index, term)
 	s.currentSnapshot = &Snapshot{index, term, machineState, snapshotPath}
 	s.saveSnapshot() 
-	s.log.Compaction(index, term)
+	s.log.Compact(index, term)
 
 
 	return NewSnapshotResponse(term, true, index), nil
@@ -849,7 +850,7 @@ func (s *Server) SnapshotRecovery(index uint64, term uint64, machineState int) (
 
 // Load a snapshot at restart
 func (s *Server) LoadSnapshot() error {
-	dir, err := os.OpenFile(s.path + "/snapshot", os.O_RDONLY, 0)
+	dir, err := os.OpenFile(path.Join(s.path, "snapshot"), os.O_RDONLY, 0)
 	if err != nil {
 		dir.Close()
 		panic(err)
@@ -869,7 +870,7 @@ func (s *Server) LoadSnapshot() error {
 
 	// not sure how many snapshot we should keep
 	sort.Strings(filenames)
-	snapshotPath := s.path + "/snapshot/" + filenames[len(filenames) - 1] 
+	snapshotPath := path.Join(s.path, "snapshot", filenames[len(filenames) - 1])
 
 	// should not file
 	file, err := os.OpenFile(snapshotPath, os.O_RDONLY, 0)
diff --git a/snapshot.go b/snapshot.go
index f2f7746..a948ac1 100644
--- a/snapshot.go
+++ b/snapshot.go
@@ -24,46 +24,6 @@ type Snapshot struct {
 	path string
 }
 
-// The request sent to a server to start from the snapshot.
-type SnapshotRequest struct {
-	LeaderName   string      `json:"leaderName"`
-	LastIndex    uint64 	 `json:"lastTerm"`
-	LastTerm	 uint64		 `json:"lastIndex"`
-	MachineState int 		 `json:"machineState"`
-}
-
-// The response returned from a server appending entries to the log.
-type SnapshotResponse struct {
-	Term        uint64 `json:"term"`
-	Success     bool   `json:"success"`
-	CommitIndex uint64 `json:"commitIndex"`
-}
-
-//------------------------------------------------------------------------------
-//
-// Constructors
-//
-//------------------------------------------------------------------------------
-
-// Creates a new Snapshot request.
-func NewSnapshotRequest(leaderName string, snapshot *Snapshot) *SnapshotRequest {
-	return &SnapshotRequest{
-		LeaderName:   leaderName,
-		LastIndex:    snapshot.lastIndex,
-		LastTerm:	  snapshot.lastTerm,
-		MachineState: snapshot.machineState,
-	}
-}
-
-// Creates a new Snapshot response.
-func NewSnapshotResponse(term uint64, success bool, commitIndex uint64) *SnapshotResponse {
-	return &SnapshotResponse{
-		Term:        term,
-		Success:     success,
-		CommitIndex: commitIndex,
-	}
-}
-
 // Save the snapshot to a file
 func (ss *Snapshot) Save() error {
 	// Write machine state to temporary buffer.