diff --git a/UPGRADING.md b/UPGRADING.md
index 42cb15c3..db83da06 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -1,6 +1,12 @@
 cos-php-sdk-v5 Upgrade Guide
 ====================
-2.0.6 to 2.0.7
+
+2.0.8 to 2.0.9
+----------
+- Fix bug of `listObjectVersions`
+- Update `getObject` with param of `saveas`
+
+2.0.7 to 2.0.8
 ----------
 - Fix presigned url when using tmpSecretId/tmpSecretKey/Token
 
diff --git a/src/Qcloud/Cos/Client.php b/src/Qcloud/Cos/Client.php
index 54af3394..f0bd21b8 100644
--- a/src/Qcloud/Cos/Client.php
+++ b/src/Qcloud/Cos/Client.php
@@ -21,7 +21,7 @@
 
 
 class Client extends GuzzleClient {
-    const VERSION = '2.0.8';
+    const VERSION = '2.0.9';
 
     public $httpClient;
     
@@ -49,6 +49,7 @@ public function __construct($cosConfig) {
         $this->cosConfig['endpoint'] = isset($cosConfig['endpoint']) ? $cosConfig['endpoint'] : 'myqcloud.com';
         $this->cosConfig['domain'] = isset($cosConfig['domain']) ? $cosConfig['domain'] : null;
         $this->cosConfig['proxy'] = isset($cosConfig['proxy']) ? $cosConfig['proxy'] : null;
+        $this->cosConfig['retry'] = isset($cosConfig['retry']) ? $cosConfig['retry'] : 1;
         $this->cosConfig['userAgent'] = isset($cosConfig['userAgent']) ? $cosConfig['userAgent'] : 'cos-php-sdk-v5.'. Client::VERSION;
         $this->cosConfig['pathStyle'] = isset($cosConfig['pathStyle']) ? $cosConfig['pathStyle'] : false;
         
@@ -113,14 +114,20 @@ public function __destruct() {
     }
 
     public function __call($method, array $args) {
-        try {
-            return parent::__call(ucfirst($method), $args);
-		} catch (CommandException $e) {
-            $previous = $e->getPrevious();
-			if ($previous !== null) {
-				throw $previous;
-			} else {
-                throw $e;
+        for ($i = 1; $i <= $this->cosConfig['retry']; $i++) {
+            try {
+                return parent::__call(ucfirst($method), $args);
+            } catch (CommandException $e) {
+                if ($i != $this->cosConfig['retry']) {
+                    sleep(1 << ($i-1));
+                    continue;
+                }
+                $previous = $e->getPrevious();
+                if ($previous !== null) {
+                    throw $previous;
+                } else {
+                    throw $e;
+                }
             }
         }
     }
@@ -137,13 +144,13 @@ private function createPresignedUrl(RequestInterface $request, $expires) {
         return $this->signature->createPresignedUrl($request, $expires);
     }
 
-    public function getPresignetUrl($method, $args, $expires = null) {
+    public function getPresignetUrl($method, $args, $expires = "+30 minutes") {
         $command = $this->getCommand($method, $args);
         $request = $this->commandToRequestTransformer($command);
         return $this->createPresignedUrl($request, $expires);
     }
 
-    public function getObjectUrl($bucket, $key, $expires = null, array $args = array()) {
+    public function getObjectUrl($bucket, $key, $expires = "+30 minutes", array $args = array()) {
         $command = $this->getCommand('GetObject', $args + array('Bucket' => $bucket, 'Key' => $key));
         $request = $this->commandToRequestTransformer($command);
         return $this->createPresignedUrl($request, $expires)->__toString();
@@ -151,7 +158,7 @@ public function getObjectUrl($bucket, $key, $expires = null, array $args = array
 
     public function upload($bucket, $key, $body, $options = array()) {
         $body = Psr7\stream_for($body);
-        $options['PartSize'] = isset($options['PartSize']) ? $options['PartSize'] : MultipartUpload::MIN_PART_SIZE;
+        $options['PartSize'] = isset($options['PartSize']) ? $options['PartSize'] : MultipartUpload::DEFAULT_PART_SIZE;
         if ($body->getSize() < $options['PartSize']) {
             $rt = $this->putObject(array(
                     'Bucket' => $bucket,
diff --git a/src/Qcloud/Cos/CommandToRequestTransformer.php b/src/Qcloud/Cos/CommandToRequestTransformer.php
index e39b7a0c..7d2bb46c 100644
--- a/src/Qcloud/Cos/CommandToRequestTransformer.php
+++ b/src/Qcloud/Cos/CommandToRequestTransformer.php
@@ -130,6 +130,7 @@ public function metadataTransformer(CommandInterface $command, $request) {
                 $request = $request->withHeader('x-cos-meta-' . $key, $value);
             }
         }
+        $request = headersMap($command, $request);  
         return $request;
     }
 
diff --git a/src/Qcloud/Cos/Common.php b/src/Qcloud/Cos/Common.php
index c188002e..e962ed47 100644
--- a/src/Qcloud/Cos/Common.php
+++ b/src/Qcloud/Cos/Common.php
@@ -33,3 +33,16 @@ function endWith($haystack, $needle) {
     }
     return (substr($haystack, -$length) === $needle);
 }
+
+function headersMap($command, $request) {
+    $headermap = array(
+            'TransferEncoding'=>'Transfer-Encoding',
+            'ChannelId'=>'x-cos-channel-id'
+    );
+    foreach ($headermap as $key => $value) {
+        if (isset($command[$key])) {
+            $request = $request->withHeader($value, $command[$key]);
+        }
+    }
+    return $request;
+}
diff --git a/src/Qcloud/Cos/Copy.php b/src/Qcloud/Cos/Copy.php
index 98ed075d..661df592 100644
--- a/src/Qcloud/Cos/Copy.php
+++ b/src/Qcloud/Cos/Copy.php
@@ -6,9 +6,6 @@
 use GuzzleHttp\Pool;
 
 class Copy {
-    /**
-     * const var: part size from 1MB to 5GB, and max parts of 10000 are allowed for each upload.
-     */
     const MIN_PART_SIZE = 1048576;
     const MAX_PART_SIZE = 5368709120;
     const DEFAULT_PART_SIZE = 52428800;
@@ -79,7 +76,7 @@ public function uploadParts($uploadId) {
                     'CopySource'=> $copySourcePath,
                     'CopySourceRange' => 'bytes='.((string)$offset).'-'.(string)($offset+$partSize - 1),
                 );
-                if(!isset($parts[$partNumber])) {
+                if(!isset($this->parts[$partNumber])) {
                     $command = $this->client->getCommand('uploadPartCopy', $params);
                     $request = $this->client->commandToRequestTransformer($command);
                     $this->commandList[$index] = $command;
@@ -103,14 +100,14 @@ public function uploadParts($uploadId) {
             },
            
             'rejected' => function ($reason, $index) { 
+                $index = $index += 1;
                 $retry = 2;
                 for ($i = 1; $i <= $retry; $i++) {
-                    $index = $index += 1;
                     try {
-                        $rt =$this->client->execute($commandList[$index]);
+                        $rt =$this->client->execute($this->commandList[$index]);
                         $part = array('PartNumber' => $index, 'ETag' => $rt['ETag']);
                         $this->parts[$index] = $part;
-                    } catch(Exception $e) {
+                    } catch(\Exception $e) {
                         if ($i == $retry) {
                             throw($e);
                         }
diff --git a/src/Qcloud/Cos/MultipartUpload.php b/src/Qcloud/Cos/MultipartUpload.php
index 94cc5bbd..604ffe4d 100644
--- a/src/Qcloud/Cos/MultipartUpload.php
+++ b/src/Qcloud/Cos/MultipartUpload.php
@@ -3,65 +3,94 @@
 namespace Qcloud\Cos;
 
 use Qcloud\Cos\Exception\CosException;
+use GuzzleHttp\Pool;
 
 class MultipartUpload {
-    /**
-     * const var: part size from 1MB to 5GB, and max parts of 10000 are allowed for each upload.
-     */
     const MIN_PART_SIZE = 1048576;
     const MAX_PART_SIZE = 5368709120;
     const DEFAULT_PART_SIZE = 52428800;
     const MAX_PARTS     = 10000;
 
     private $client;
-    private $body;
     private $options;
     private $partSize;
+    private $parts;
+    private $body;
 
     public function __construct($client, $body, $options = array()) {
-        $this->client = $client;
+        $minPartSize = $options['PartSize'];
+        unset($options['PartSize']);
         $this->body = $body;
+        $this->client = $client;
         $this->options = $options;
-        $this->partSize = $this->calculatePartSize($options['PartSize']);
-        unset($options['PartSize']);
+        $this->partSize = $this->calculatePartSize($minPartSize);
+        $this->concurrency = isset($options['Concurrency']) ? $options['Concurrency'] : 10;
+        $this->parts = [];
+        $this->partNumberList = [];
     }
-
     public function performUploading() {
-        $rt = $this->initiateMultipartUpload();
-        $uploadId = $rt['UploadId'];
-        $partNumber = 1;
-        $parts = array();
-        for (;;) {
-            if ($this->body->eof()) {
-                break;
-            }
-            $body = $this->body->read($this->partSize);
-            if (empty($body)) {
-                break;
+        $uploadId= $this->initiateMultipartUpload();
+        $this->uploadParts($uploadId);
+        foreach ( $this->parts as $key => $row ){
+            $num1[$key] = $row ['PartNumber'];
+            $num2[$key] = $row ['ETag'];
+        }
+        array_multisort($num1, SORT_ASC, $num2, SORT_ASC, $this->parts);
+        return $this->client->completeMultipartUpload(array(
+            'Bucket' => $this->options['Bucket'],
+            'Key' => $this->options['Key'],
+            'UploadId' => $uploadId,
+            'Parts' => $this->parts)
+        );
+
+    }
+    public function uploadParts($uploadId) {
+        $uploadRequests = function ($uploadId) {
+            $partNumber = 1;
+            $index = 1;
+            for ( ; ; $partNumber ++) {
+                if ($this->body->eof()) {
+                    break;
+                }
+                $body = $this->body->read($this->partSize);
+                if (empty($body)) {
+                    break;
+                }
+                if (isset($this->parts[$partNumber])) {
+                    continue;
+                }
+                $this->partNumberList[$index] = $partNumber;
+                $params = array(
+                    'Bucket' => $this->options['Bucket'],
+                    'Key' => $this->options['Key'],
+                    'UploadId' => $uploadId,
+                    'PartNumber' => $partNumber,
+                    'Body' => $body
+                );
+                if(!isset($this->parts[$partNumber])) {
+                    $command = $this->client->getCommand('uploadPart', $params);
+                    $request = $this->client->commandToRequestTransformer($command);
+                    $index ++;
+                    yield $request;
+                }
             }
-            $result = $this->client->uploadPart(array(
-                        'Bucket' => $this->options['Bucket'],
-                        'Key' => $this->options['Key'],
-                        'Body' => $body,
-                        'UploadId' => $uploadId,
-                        'PartNumber' => $partNumber));
-            if (md5($body) != substr($result['ETag'], 1, -1)){
-                throw new CosException("ETag check inconsistency");
+        };
+        $pool = new Pool($this->client->httpClient, $uploadRequests($uploadId), [
+            'concurrency' => $this->concurrency,
+            'fulfilled' => function ($response, $index) {
+                $index = $index + 1;
+                $partNumber = $this->partNumberList[$index];
+                $etag = $response->getHeaders()["ETag"][0];
+                $part = array('PartNumber' => $partNumber, 'ETag' => $etag);
+                $this->parts[$partNumber] = $part;
+            },
+           
+            'rejected' => function ($reason, $index) {
+                throw($reason);
             }
-            $part = array('PartNumber' => $partNumber, 'ETag' => $result['ETag']);
-            array_push($parts, $part);
-            ++$partNumber;
-        }
-        try {
-            $rt = $this->client->completeMultipartUpload(array(
-                'Bucket' => $this->options['Bucket'],
-                'Key' => $this->options['Key'],
-                'UploadId' => $uploadId,
-                'Parts' => $parts));
-        } catch(\Exception $e){
-            throw $e;
-        }
-        return $rt;
+        ]);
+        $promise = $pool->promise();
+        $promise->wait();
     }
 
     public function resumeUploading() {
@@ -73,54 +102,35 @@ public function resumeUploading() {
                 $parts = array();
         if (count($rt['Parts']) > 0) {
             foreach ($rt['Parts'] as $part) {
-                $parts[$part['PartNumber'] - 1] = array('PartNumber' => $part['PartNumber'], 'ETag' => $part['ETag']);
+                $this->parts[$part['PartNumber']] = array('PartNumber' => $part['PartNumber'], 'ETag' => $part['ETag']);
             }
         }
-        for ($partNumber = 1;;++$partNumber) {
-            if ($this->body->eof()) {
-                break;
-            }
-            $body = $this->body->read($this->partSize);
-
-            if (array_key_exists($partNumber-1, $parts)){
-
-                if (md5($body) != substr($parts[$partNumber-1]['ETag'], 1, -1)){
-                    throw new CosException("ETag check inconsistency");
-                }
-                continue;
-            }
-
-            $result = $this->client->uploadPart(array(
-                'Bucket' => $this->options['Bucket'],
-                'Key' => $this->options['Key'],
-                'Body' => $body,
-                'UploadId' => $uploadId,
-                'PartNumber' => $partNumber));
-            if (md5($body) != substr($result['ETag'], 1, -1)){
-                throw new CosException("ETag check inconsistency");
-            }
-            $parts[$partNumber-1] = array('PartNumber' => $partNumber, 'ETag' => $result['ETag']);
-
+        $this->uploadParts($uploadId);
+        foreach ( $this->parts as $key => $row ){
+            $num1[$key] = $row ['PartNumber'];
+            $num2[$key] = $row ['ETag'];
         }
-        $rt = $this->client->completeMultipartUpload(array(
+        array_multisort($num1, SORT_ASC, $num2, SORT_ASC, $this->parts);
+        return $this->client->completeMultipartUpload(array(
             'Bucket' => $this->options['Bucket'],
             'Key' => $this->options['Key'],
             'UploadId' => $uploadId,
-            'Parts' => $parts));
-        return $rt;
+            'Parts' => $this->parts)
+        );
     }
 
-    private function calculatePartSize($minPartSize) {
+    private function calculatePartSize($minPartSize)
+    {   
         $partSize = intval(ceil(($this->body->getSize() / self::MAX_PARTS)));
         $partSize = max($minPartSize, $partSize);
         $partSize = min($partSize, self::MAX_PART_SIZE);
         $partSize = max($partSize, self::MIN_PART_SIZE);
-
         return $partSize;
     }
 
     private function initiateMultipartUpload() {
         $result = $this->client->createMultipartUpload($this->options);
-        return $result;
+        return $result['UploadId'];
     }
+
 }
diff --git a/src/Qcloud/Cos/ResultTransformer.php b/src/Qcloud/Cos/ResultTransformer.php
index 02afc84c..7764e427 100644
--- a/src/Qcloud/Cos/ResultTransformer.php
+++ b/src/Qcloud/Cos/ResultTransformer.php
@@ -33,7 +33,15 @@ public function writeDataToLocal(CommandInterface $command, RequestInterface $re
         if ($action == "GetObject") {
             if (isset($command['SaveAs'])) {
                 $fp = fopen($command['SaveAs'], "wb");
-                fwrite($fp, $response->getBody());
+                $stream = $response->getBody();
+                $offset = 0;
+                $partsize = 8192;
+                while (!$stream->eof()) {
+                    $output = $stream->read($partsize);
+                    fseek($fp, $offset);
+                    fwrite($fp, $output);
+                    $offset += $partsize;
+                }
                 fclose($fp);
             }
         }
diff --git a/src/Qcloud/Cos/Service.php b/src/Qcloud/Cos/Service.php
index ffd3a3e0..2b805a3e 100644
--- a/src/Qcloud/Cos/Service.php
+++ b/src/Qcloud/Cos/Service.php
@@ -3430,13 +3430,17 @@ public static function getService() {
                                 'type' => 'object',
                                 'properties' => array(
                                     'Status' => array(
-                                        'type' => 'string'),
+                                        'type' => 'string'
+                                    ),
                                     'Name' => array(
-                                        'type' => 'string'),
+                                        'type' => 'string'
+                                    ),
                                     'Type' => array(
-                                        'type' => 'string'),
+                                        'type' => 'string'
+                                    ),
                                     'ForcedReplacement' => array(
-                                        'type' => 'string'),
+                                        'type' => 'string'
+                                    ),
                                 ),
                             ),
                         ),
@@ -4454,10 +4458,9 @@ public static function getService() {
                             'type' => 'string',
                             'location' => 'xml',
                         ),
-                        'Versions' => array(
+                        'Version' => array(
                             'type' => 'array',
                             'location' => 'xml',
-                            'sentAs' => 'Versions',
                             'data' => array(
                                 'xmlFlattened' => true,
                             ),
diff --git a/src/Qcloud/Cos/Signature.php b/src/Qcloud/Cos/Signature.php
index a9e03930..72e3ecbb 100644
--- a/src/Qcloud/Cos/Signature.php
+++ b/src/Qcloud/Cos/Signature.php
@@ -20,6 +20,9 @@ public function signRequest(RequestInterface $request) {
         return $request->withHeader('Authorization', $authorization);
     }
     public function createAuthorization(RequestInterface $request, $expires = "+30 minutes") {
+        if (is_null($expires)) {
+            $expires = "+30 minutes";
+        }
         $signTime = (string)(time() - 60) . ';' . (string)(strtotime($expires));
         $httpString = strtolower($request->getMethod()) . "\n" . urldecode($request->getUri()->getPath()) .
             "\n\nhost=" . $request->getHeader("Host")[0]. "\n";
diff --git a/src/Qcloud/Cos/Tests/Test.php b/src/Qcloud/Cos/Tests/COSTest.php
similarity index 99%
rename from src/Qcloud/Cos/Tests/Test.php
rename to src/Qcloud/Cos/Tests/COSTest.php
index e78724a3..b0ad6d7a 100644
--- a/src/Qcloud/Cos/Tests/Test.php
+++ b/src/Qcloud/Cos/Tests/COSTest.php
@@ -68,7 +68,6 @@ public function testValidRegionBucket()
         $regionlist = array('cn-east','ap-shanghai',
         'cn-south','ap-guangzhou',
         'cn-north','ap-beijing-1',
-        'cn-south-2','ap-guangzhou-2',
         'cn-southwest','ap-chengdu',
         'sg','ap-singapore',
         'tj','ap-beijing-1',