diff --git a/README.md b/README.md
index 68c940a..6234fac 100644
--- a/README.md
+++ b/README.md
@@ -6,8 +6,8 @@ This repository contains resources and configuration scripts for building a cust
 
 ## Supported OS
 
-* CentOS 7.6/7.7/7.8/7.9
 * Aliyun Linux 2 (Alibaba Cloud Linux 2)
+* CentOS 7.6/7.7/7.8/7.9
 
 ## Setup
 
@@ -35,7 +35,7 @@ export RUNTIME=XXX
 export ALICLOUD_REGION=XXX
 export ALICLOUD_ACCESS_KEY=XXX
 export ALICLOUD_SECRET_KEY=XXX
-packer build examples/ack-optimized-os-1.20.json
+packer build examples/ack-optimized-os-1.18.json
 ```
 NOTE: `RUNTIME` only support `docker` and `containerd`
 
diff --git a/examples/ack-aliyunlinux2.json b/examples/ack-aliyunlinux2.json
index 0ac1fd0..76fc160 100644
--- a/examples/ack-aliyunlinux2.json
+++ b/examples/ack-aliyunlinux2.json
@@ -3,7 +3,7 @@
     "region": "cn-hangzhou",
     "image_name": "test_image{{timestamp}}",
     "source_image": "aliyun_2_1903_x64_20G_alibase_20210120.vhd",
-    "instance_type": "ecs.g6.large",
+    "instance_type": "ecs.g6.2xlarge",
     "access_key": "{{env `ALICLOUD_ACCESS_KEY`}}",
     "secret_key": "{{env `ALICLOUD_SECRET_KEY`}}"
   },
diff --git a/examples/ack-centos-using-existing-vpc-vswitch.json b/examples/ack-centos-using-existing-vpc-vswitch.json
index dcd3ed9..0f8454f 100644
--- a/examples/ack-centos-using-existing-vpc-vswitch.json
+++ b/examples/ack-centos-using-existing-vpc-vswitch.json
@@ -3,7 +3,7 @@
     "region": "cn-hangzhou",
     "image_name": "test_image{{timestamp}}",
     "source_image": "centos_7_9_x64_20G_alibase_20210128.vhd",
-    "instance_type": "ecs.g6.large",
+    "instance_type": "ecs.g6.2xlarge",
     "vpc_id": "vpc-xxxxxx",
     "vswitch_id": "vsw-xxxxxx",
     "access_key": "{{env `ALICLOUD_ACCESS_KEY`}}",
diff --git a/examples/ack-centos.json b/examples/ack-centos.json
index 5a79efc..8abe0ab 100644
--- a/examples/ack-centos.json
+++ b/examples/ack-centos.json
@@ -3,7 +3,7 @@
     "region": "cn-hangzhou",
     "image_name": "test_image{{timestamp}}",
     "source_image": "centos_7_9_x64_20G_alibase_20210128.vhd",
-    "instance_type": "ecs.g6.large",
+    "instance_type": "ecs.g6.2xlarge",
     "access_key": "{{env `ALICLOUD_ACCESS_KEY`}}",
     "secret_key": "{{env `ALICLOUD_SECRET_KEY`}}"
   },
diff --git a/examples/ack-optimized-os-1.18.json b/examples/ack-optimized-os-1.18.json
index b5f5368..5dfa5cd 100644
--- a/examples/ack-optimized-os-1.18.json
+++ b/examples/ack-optimized-os-1.18.json
@@ -2,7 +2,7 @@
   "variables": {
     "image_name": "ack-optimized_image-1.18-{{timestamp}}",
     "source_image": "aliyun_2_1903_x64_20G_alibase_20210120.vhd",
-    "instance_type": "ecs.g6.large",
+    "instance_type": "ecs.g6.2xlarge",
     "region": "{{env `ALICLOUD_REGION`}}",
     "access_key": "{{env `ALICLOUD_ACCESS_KEY`}}",
     "secret_key": "{{env `ALICLOUD_SECRET_KEY`}}",
diff --git a/examples/ack-optimized-os-1.20.json b/examples/ack-optimized-os-1.20.json
index c56c445..afee1bb 100644
--- a/examples/ack-optimized-os-1.20.json
+++ b/examples/ack-optimized-os-1.20.json
@@ -2,7 +2,7 @@
   "variables": {
     "image_name": "ack-optimized_image-1.20-{{timestamp}}",
     "source_image": "aliyun_2_1903_x64_20G_alibase_20210120.vhd",
-    "instance_type": "ecs.g6.large",
+    "instance_type": "ecs.g6.2xlarge",
     "region": "{{env `ALICLOUD_REGION`}}",
     "access_key": "{{env `ALICLOUD_ACCESS_KEY`}}",
     "secret_key": "{{env `ALICLOUD_SECRET_KEY`}}",