diff --git a/pkg/drivers/posix/posix/posix.go b/pkg/drivers/posix/posix/posix.go
index c6b8acbd..3d292396 100644
--- a/pkg/drivers/posix/posix/posix.go
+++ b/pkg/drivers/posix/posix/posix.go
@@ -618,11 +618,11 @@ func (s *PosixStorage) UploadLink(fileUploadArg *models.FileUploadArgs) ([]byte,
 				return nil, err
 			}
 		} else if fileUploadArg.FileParam.FileType == common.External {
-			uri, err := fileUploadArg.FileParam.GetResourceUri()
+			diskCheckPath, err := fileUploadArg.FileParam.GetDiskCheckPath()
 			if err != nil {
-				return nil, err
+				return nil, fmt.Errorf("get disk check path error: %v", err)
 			}
-			_, err = common.CheckDiskSpace(uri, fileUploadArg.TotalSize, false)
+			_, err = common.CheckDiskSpace(diskCheckPath, fileUploadArg.TotalSize, false)
 			if err != nil {
 				return nil, err
 			}
diff --git a/pkg/models/file_param.go b/pkg/models/file_param.go
index 9691f827..40ffab92 100644
--- a/pkg/models/file_param.go
+++ b/pkg/models/file_param.go
@@ -254,6 +254,23 @@ func (r *FileParam) IsSystem() bool {
 	return r.FileType == common.Drive || r.FileType == common.Cache || r.FileType == common.Data
 }
 
+// GetDiskCheckPath returns the filesystem path for disk usage checking.
+// For external mounted disks, it appends the disk name (first component of Path)
+// to the base URI so that statfs can identify the correct mount point.
+func (r *FileParam) GetDiskCheckPath() (string, error) {
+	uri, err := r.GetResourceUri()
+	if err != nil {
+		return "", err
+	}
+	if r.FileType == common.External && r.Path != "" {
+		parts := strings.SplitN(strings.TrimPrefix(r.Path, "/"), "/", 2)
+		if parts[0] != "" {
+			return filepath.Join(uri, parts[0]), nil
+		}
+	}
+	return uri, nil
+}
+
 func (r *FileParam) IsFile() (string, bool) {
 	if r.Path == "" || r.Path == "/" || strings.HasSuffix(r.Path, "/") {
 		return "", false
diff --git a/pkg/tasks/task_paste_cloud.go b/pkg/tasks/task_paste_cloud.go
index d1a3fdd6..2be4ba07 100644
--- a/pkg/tasks/task_paste_cloud.go
+++ b/pkg/tasks/task_paste_cloud.go
@@ -97,7 +97,11 @@ func (t *Task) DownloadFromCloud() error {
 		return err
 	}
 
-	posixSize, err := common.CheckDiskSpace(dstUri, cloudSize, true)
+	diskCheckPath, err := dst.GetDiskCheckPath()
+	if err != nil {
+		return fmt.Errorf("get disk check path error: %v", err)
+	}
+	posixSize, err := common.CheckDiskSpace(diskCheckPath, cloudSize, dst.IsSystem())
 	if err != nil {
 		klog.Errorf("get posix free space size error: %v", err)
 		return err
diff --git a/pkg/tasks/task_paste_download.go b/pkg/tasks/task_paste_download.go
index 2b57223e..b5fb7f1f 100644
--- a/pkg/tasks/task_paste_download.go
+++ b/pkg/tasks/task_paste_download.go
@@ -108,7 +108,11 @@ func (t *Task) DownloadFromFiles() error {
 		klog.Errorf("[Task] Id: %s, dst uri found error: %v", t.id, err)
 		return err
 	}
-	localSpace, err := common.CheckDiskSpace(dstUri, totalSize, dst.IsSystem()) // no sync dst but external here, IsSystem() is enough and precise
+	diskCheckPath, err := dst.GetDiskCheckPath()
+	if err != nil {
+		return fmt.Errorf("get disk check path error: %v", err)
+	}
+	localSpace, err := common.CheckDiskSpace(diskCheckPath, totalSize, dst.IsSystem()) // no sync dst but external here, IsSystem() is enough and precise
 	if err != nil {
 		return err
 	}
diff --git a/pkg/tasks/task_paste_posix.go b/pkg/tasks/task_paste_posix.go
index 1a642a8e..7364b741 100644
--- a/pkg/tasks/task_paste_posix.go
+++ b/pkg/tasks/task_paste_posix.go
@@ -57,7 +57,11 @@ func (t *Task) Rsync() error {
 	klog.Infof("[Task] Id: %s, srcPath: %s, dstUri: %s, srcMeta: %s", t.id, srcPath, dstUri, common.ToJson(pathMeta))
 
 	// check free space
-	dstFree, err := common.CheckDiskSpace(dstUri, pathMeta.Size, dst.IsSystem()) // no sync dst but external here, IsSystem() is enough and precise
+	diskCheckPath, err := dst.GetDiskCheckPath()
+	if err != nil {
+		return fmt.Errorf("get disk check path error: %v", err)
+	}
+	dstFree, err := common.CheckDiskSpace(diskCheckPath, pathMeta.Size, dst.IsSystem()) // no sync dst but external here, IsSystem() is enough and precise
 	if err != nil {
 		return err
 	}
diff --git a/pkg/tasks/task_paste_sync.go b/pkg/tasks/task_paste_sync.go
index c4bd6fdf..e535d0fa 100644
--- a/pkg/tasks/task_paste_sync.go
+++ b/pkg/tasks/task_paste_sync.go
@@ -99,11 +99,11 @@ func (t *Task) DownloadFromSync() error {
 		return err
 	}
 
-	dstUri, err := dst.GetResourceUri()
+	diskCheckPath, err := dst.GetDiskCheckPath()
 	if err != nil {
-		return err
+		return fmt.Errorf("get disk check path error: %v", err)
 	}
-	dstSize, err := common.CheckDiskSpace(dstUri, srcTotalSize, true)
+	dstSize, err := common.CheckDiskSpace(diskCheckPath, srcTotalSize, dst.IsSystem())
 	if err != nil {
 		klog.Errorf("get posix free space size error: %v", err)
 		return err