diff --git a/manual/extension/only_office.md b/manual/extension/only_office.md
index f7bfabfb..cf8c2d3e 100644
--- a/manual/extension/only_office.md
+++ b/manual/extension/only_office.md
@@ -50,6 +50,7 @@ ONLYOFFICE_JWT_SECRET = '<your jwt secret>'
 # If you have custom needs, you can also configure them, which will override the default values.
 ONLYOFFICE_FILE_EXTENSION = ('doc', 'docx', 'ppt', 'pptx', 'xls', 'xlsx', 'odt', 'fodt', 'odp', 'fodp', 'ods', 'fods', 'ppsx', 'pps', 'csv')
 ONLYOFFICE_EDIT_FILE_EXTENSION = ('docx', 'pptx', 'xlsx', 'csv')
+OFFICE_PREVIEW_MAX_SIZE = 30 * 1024 * 1024 # preview size, 30 MB
 ```
 
 !!! tip
@@ -139,6 +140,7 @@ In general, you only need to specify the values ​​of the following fields in
 ENABLE_ONLYOFFICE = True
 ONLYOFFICE_APIJS_URL = 'http{s}://<Your OnlyOffice host url>/web-apps/apps/api/documents/api.js'
 ONLYOFFICE_JWT_SECRET = '<your jwt secret>'
+OFFICE_PREVIEW_MAX_SIZE = 30 * 1024 * 1024 # preview size, 30 MB
 ```
 
 ### About SSL
diff --git a/manual/images/seafile-cluster-arch.png b/manual/images/seafile-cluster-arch.png
index 6775a191..fb15e54e 100644
Binary files a/manual/images/seafile-cluster-arch.png and b/manual/images/seafile-cluster-arch.png differ
diff --git a/manual/repo/k8s/cluster/seafile-backend-deployment.yaml b/manual/repo/k8s/cluster/seafile-backend-deployment.yaml
index ea2332bb..f327a33f 100644
--- a/manual/repo/k8s/cluster/seafile-backend-deployment.yaml
+++ b/manual/repo/k8s/cluster/seafile-backend-deployment.yaml
@@ -52,16 +52,6 @@ spec:
                 configMapKeyRef:
                   name: seafile-env
                   key: SITE_ROOT
-            - name: ENABLE_SEADOC
-              valueFrom:
-                configMapKeyRef:
-                  name: seafile-env
-                  key: ENABLE_SEADOC
-            - name: SEADOC_SERVER_URL
-              valueFrom:
-                configMapKeyRef:
-                  name: seafile-env
-                  key: SEADOC_SERVER_URL
             - name: SEAFILE_MYSQL_DB_HOST
               valueFrom:
                 configMapKeyRef:
diff --git a/manual/setup/cluster_deploy_with_docker.md b/manual/setup/cluster_deploy_with_docker.md
index c91bb2ee..15b00342 100644
--- a/manual/setup/cluster_deploy_with_docker.md
+++ b/manual/setup/cluster_deploy_with_docker.md
@@ -4,7 +4,7 @@
 
 The Seafile cluster solution employs a 3-tier architecture:
 
-* Load balancer tier: Distribute incoming traffic to Seafile servers. HA can be achieved by deploying multiple load balancer instances.
+* Load balancer tier: Distribute incoming traffic to Seafile servers. HA (high availability) can be achieved by deploying multiple load balancer instances.
 * Seafile server cluster: a cluster of Seafile server instances. If one instance fails, the load balancer will stop handing traffic to it. So HA is achieved.
 * Backend storage: Distributed storage cluster, e.g.  S3, Openstack Swift or Ceph.
 
@@ -48,9 +48,6 @@ Please refer [here](./system_requirements.md#seafile-cluster) for the details ab
 
 2. Pulling Seafile image
 
-    !!! tip
-        Since v12.0, Seafile PE versions are hosted on DockerHub and does not require username and password to download.
-
     ```bash
     docker pull seafileltd/seafile-pro-mc:13.0-latest
     ```
@@ -78,7 +75,7 @@ Please refer [here](./system_requirements.md#seafile-cluster) for the details ab
 
     !!! success "Cluster init mode"
     
-        Because CLUSTER_INIT_MODE is true in the `.env` file, Seafile docker will be started in init mode and generate configuration files. As the results, you can see the following lines if you trace the Seafile container (i.e., `docker logs seafile`):
+        Because `CLUSTER_INIT_MODE` is true in the `.env` file, Seafile docker will be started in init mode and generate configuration files. As the results, you can see the following lines if you trace the Seafile container (i.e., `docker logs seafile`):
 
         ```log
         ---------------------------------
diff --git a/manual/setup_binary/cluster_deployment.md b/manual/setup_binary/cluster_deployment.md
index f2af8a7d..581d70ca 100644
--- a/manual/setup_binary/cluster_deployment.md
+++ b/manual/setup_binary/cluster_deployment.md
@@ -454,7 +454,6 @@ For **seafile.conf**:
 ```
 [cluster]
 enabled = true
-memcached_options = --SERVER=<IP of memcached node> --POOL-MIN=10 --POOL-MAX=100
 
 ```