diff --git a/README.md b/README.md
index 31410a17c..de37023f1 100755
--- a/README.md
+++ b/README.md
@@ -530,7 +530,8 @@ Supported operating systems and hardware:
 
 ### SRS 2.0 history
 
-* v2.0, 2015-02-19, refine pithy print to more easyer to use 2.0.121.
+* v2.0, 2015-02-19, refine dvr, append file when dvr file exists. 2.0.122.
+* v2.0, 2015-02-19, refine pithy print to more easyer to use. 2.0.121.
 * v2.0, 2015-02-18, fix [#133](https://github.com/winlinvip/simple-rtmp-server/issues/133), support push rtsp to srs. 2.0.120.
 * v2.0, 2015-02-17, the join maybe failed, should use a variable to ensure thread terminated. 2.0.119.
 * v2.0, 2015-02-15, for [#304](https://github.com/winlinvip/simple-rtmp-server/issues/304), support config default acodec/vcodec. 2.0.118.
diff --git a/trunk/conf/full.conf b/trunk/conf/full.conf
index 4ef6d6ede..a8a92994b 100644
--- a/trunk/conf/full.conf
+++ b/trunk/conf/full.conf
@@ -1227,4 +1227,5 @@ vhost removed.srs.com {
 # config for the pithy print,
 # which always print constant message specified by interval,
 # whatever the clients in concurrency.
+# default: 10000
 pithy_print_ms      10000;
diff --git a/trunk/src/app/srs_app_dvr.cpp b/trunk/src/app/srs_app_dvr.cpp
index bc7e32624..48c252f32 100644
--- a/trunk/src/app/srs_app_dvr.cpp
+++ b/trunk/src/app/srs_app_dvr.cpp
@@ -368,11 +368,27 @@ int SrsDvrPlan::flv_open(string stream, string path)
     int ret = ERROR_SUCCESS;
     
     segment->reset();
+
+    if (srs_path_exists(path)) {
+        // when path exists, always append to it.
+        // so we must use the target flv path as output flv.
+        tmp_flv_file = path;
+    } else {
+        // when path not exists, dvr to tmp file.
+        tmp_flv_file = path + ".tmp";
+    }
     
-    std::string tmp_file = path + ".tmp";
-    if ((ret = fs->open(tmp_file)) != ERROR_SUCCESS) {
-        srs_error("open file stream for file %s failed. ret=%d", path.c_str(), ret);
-        return ret;
+    if (srs_path_exists(path)) {
+        if ((ret = fs->open_append(tmp_flv_file)) != ERROR_SUCCESS) {
+            srs_error("append file stream for file %s failed. ret=%d", path.c_str(), ret);
+            return ret;
+        }
+        srs_warn("dvr: always append to when exists, file=%s.", path.c_str());
+    } else {
+        if ((ret = fs->open(tmp_flv_file)) != ERROR_SUCCESS) {
+            srs_error("open file stream for file %s failed. ret=%d", path.c_str(), ret);
+            return ret;
+        }
     }
     
     if ((ret = enc->initialize(fs)) != ERROR_SUCCESS) {
@@ -396,12 +412,14 @@ int SrsDvrPlan::flv_close()
     
     fs->close();
     
-    std::string tmp_file = segment->path + ".tmp";
-    if (rename(tmp_file.c_str(), segment->path.c_str()) < 0) {
-        ret = ERROR_SYSTEM_FILE_RENAME;
-        srs_error("rename flv file failed, %s => %s. ret=%d", 
-            tmp_file.c_str(), segment->path.c_str(), ret);
-        return ret;
+    // when tmp flv file exists, reap it.
+    if (tmp_flv_file != segment->path) {
+        if (rename(tmp_flv_file.c_str(), segment->path.c_str()) < 0) {
+            ret = ERROR_SYSTEM_FILE_RENAME;
+            srs_error("rename flv file failed, %s => %s. ret=%d", 
+                tmp_flv_file.c_str(), segment->path.c_str(), ret);
+            return ret;
+        }
     }
     
 #ifdef SRS_AUTO_HTTP_CALLBACK
diff --git a/trunk/src/app/srs_app_dvr.hpp b/trunk/src/app/srs_app_dvr.hpp
index 5ffffa17c..d879c9e0c 100644
--- a/trunk/src/app/srs_app_dvr.hpp
+++ b/trunk/src/app/srs_app_dvr.hpp
@@ -111,6 +111,8 @@ protected:
     SrsRequest* _req;
     bool dvr_enabled;
     SrsFileWriter* fs;
+private:
+    std::string tmp_flv_file;
 public:
     SrsDvrPlan();
     virtual ~SrsDvrPlan();
diff --git a/trunk/src/app/srs_app_http.cpp b/trunk/src/app/srs_app_http.cpp
index 40981d0fd..9333f7af5 100644
--- a/trunk/src/app/srs_app_http.cpp
+++ b/trunk/src/app/srs_app_http.cpp
@@ -294,8 +294,7 @@ int SrsGoHttpFileServer::serve_http(ISrsGoHttpResponseWriter* w, SrsHttpMessage*
     }
     
     // stat current dir, if exists, return error.
-    struct stat st;
-    if (stat(fullpath.c_str(), &st) != 0) {
+    if (!srs_path_exists(fullpath)) {
         srs_warn("http miss file=%s, pattern=%s, upath=%s", 
             fullpath.c_str(), entry->pattern.c_str(), upath.c_str());
         return SrsGoHttpNotFoundHandler().serve_http(w, r);
diff --git a/trunk/src/core/srs_core.hpp b/trunk/src/core/srs_core.hpp
index 75d20939d..96dc21cdd 100644
--- a/trunk/src/core/srs_core.hpp
+++ b/trunk/src/core/srs_core.hpp
@@ -31,7 +31,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // current release version
 #define VERSION_MAJOR       2
 #define VERSION_MINOR       0
-#define VERSION_REVISION    121
+#define VERSION_REVISION    122
 
 // server info.
 #define RTMP_SIG_SRS_KEY "SRS"
diff --git a/trunk/src/kernel/srs_kernel_file.cpp b/trunk/src/kernel/srs_kernel_file.cpp
index b724ac2a1..f5b08a5b6 100644
--- a/trunk/src/kernel/srs_kernel_file.cpp
+++ b/trunk/src/kernel/srs_kernel_file.cpp
@@ -69,6 +69,30 @@ int SrsFileWriter::open(string file)
     return ret;
 }
 
+int SrsFileWriter::open_append(string file)
+{
+    int ret = ERROR_SUCCESS;
+    
+    if (fd > 0) {
+        ret = ERROR_SYSTEM_FILE_ALREADY_OPENED;
+        srs_error("file %s already opened. ret=%d", _file.c_str(), ret);
+        return ret;
+    }
+    
+    int flags = O_APPEND|O_WRONLY;
+    mode_t mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH;
+
+    if ((fd = ::open(file.c_str(), flags, mode)) < 0) {
+        ret = ERROR_SYSTEM_FILE_OPENE;
+        srs_error("open file %s failed. ret=%d", file.c_str(), ret);
+        return ret;
+    }
+    
+    _file = file;
+    
+    return ret;
+}
+
 void SrsFileWriter::close()
 {
     int ret = ERROR_SUCCESS;
diff --git a/trunk/src/kernel/srs_kernel_file.hpp b/trunk/src/kernel/srs_kernel_file.hpp
index b870f0128..31857ba13 100644
--- a/trunk/src/kernel/srs_kernel_file.hpp
+++ b/trunk/src/kernel/srs_kernel_file.hpp
@@ -47,6 +47,10 @@ public:
     * open file writer, can open then close then open...
     */
     virtual int open(std::string file);
+    /**
+    * open file writer in append mode.
+    */
+    virtual int open_append(std::string file);
     virtual void close();
 public:
     virtual bool is_open();
diff --git a/trunk/src/kernel/srs_kernel_utility.cpp b/trunk/src/kernel/srs_kernel_utility.cpp
index 4fc079f35..3a2eeebda 100644
--- a/trunk/src/kernel/srs_kernel_utility.cpp
+++ b/trunk/src/kernel/srs_kernel_utility.cpp
@@ -230,10 +230,8 @@ int __srs_create_dir_recursively(string dir)
 {
     int ret = ERROR_SUCCESS;
     
-    struct stat st;
-    
     // stat current dir, if exists, return error.
-    if (stat(dir.c_str(), &st) == 0) {
+    if (srs_path_exists(dir)) {
         return ERROR_SYSTEM_DIR_EXISTS;
     }
     
@@ -279,6 +277,18 @@ int srs_create_dir_recursively(string dir)
     return ret;
 }
 
+bool srs_path_exists(std::string path)
+{
+    struct stat st;
+    
+    // stat current dir, if exists, return error.
+    if (stat(path.c_str(), &st) == 0) {
+        return true;
+    }
+
+    return false;
+}
+
 bool srs_avc_startswith_annexb(SrsStream* stream, int* pnb_start_code)
 {
     char* bytes = stream->data() + stream->pos();
diff --git a/trunk/src/kernel/srs_kernel_utility.hpp b/trunk/src/kernel/srs_kernel_utility.hpp
index 0a780c668..d5a514878 100644
--- a/trunk/src/kernel/srs_kernel_utility.hpp
+++ b/trunk/src/kernel/srs_kernel_utility.hpp
@@ -64,6 +64,9 @@ extern bool srs_string_ends_with(std::string str, std::string flag);
 // create dir recursively
 extern int srs_create_dir_recursively(std::string dir);
 
+// whether path exists.
+extern bool srs_path_exists(std::string path);
+
 /**
 * whether stream starts with the avc NALU in "AnnexB" 
 * from H.264-AVC-ISO_IEC_14496-10.pdf, page 211.