diff --git a/xCAT-server/lib/xcat/plugins/iscsi.pm b/xCAT-server/lib/xcat/plugins/iscsi.pm
index eb9bc93c2..f8d84f818 100644
--- a/xCAT-server/lib/xcat/plugins/iscsi.pm
+++ b/xCAT-server/lib/xcat/plugins/iscsi.pm
@@ -114,6 +114,7 @@ sub process_request {
          %rsp=(name=>[$node]);
          $lunsize -= 1;
          my $rc = system("dd if=/dev/zero of=$fileloc bs=1M count=1 seek=$lunsize");
+         $lunsize += 1;
          if ($rc) {
             $rsp{error}=["dd process exited with return code $rc"];
             $rsp{errorcode} = [1];