anchor.diff:  [id="migration-preparing-storage"]
   === Storage considerations
   
  -Review the following storage changes to consider when transitioning from {product-title} 3.11 to {product-title} 4.4.
  +Review the following storage changes to consider when transitioning from {product-title} 3.11 to {product-title} 4.5.
   
   [discrete]
   ==== Local volume persistent storage
   
  -Local storage is only supported by using the Local Storage Operator in {product-title} 4.4. It is not supported to use the local provisioner method from {product-title} 3.11.
  +Local storage is only supported by using the Local Storage Operator in {product-title} 4.5. It is not supported to use the local provisioner method from {product-title} 3.11.
   
   For more information, see xref:../../storage/persistent_storage/persistent-storage-local.adoc#persistent-storage-using-local-volume[Persistent storage using local volumes].
   
   [discrete]
   ==== FlexVolume persistent storage
   
  -The FlexVolume plug-in location changed from {product-title} 3.11. The new location in {product-title} 4.4 is `/etc/kubernetes/kubelet-plugins/volume/exec`. Attachable FlexVolume plug-ins are no longer supported.
  +The FlexVolume plug-in location changed from {product-title} 3.11. The new location in {product-title} 4.5 is `/etc/kubernetes/kubelet-plugins/volume/exec`. Attachable FlexVolume plug-ins are no longer supported.
   
   For more information, see xref:../../storage/persistent_storage/persistent-storage-flexvolume.adoc#persistent-storage-using-flexvolume[Persistent storage using FlexVolume].
   
   [discrete]
   ==== Container Storage Interface (CSI) persistent storage
   
  -Persistent storage using the Container Storage Interface (CSI) was link:https://access.redhat.com/support/offerings/techpreview[Technology Preview] in {product-title} 3.11. CSI version 1.1.0 is fully supported in {product-title} 4.4, but does not ship with any CSI drivers. You must install your own driver.
  +Persistent storage using the Container Storage Interface (CSI) was link:https://access.redhat.com/support/offerings/techpreview[Technology Preview] in {product-title} 3.11. CSI version 1.1.0 is fully supported in {product-title} 4.5, but does not ship with any CSI drivers. You must install your own driver.
   
   For more information, see xref:../../storage/container_storage_interface/persistent-storage-csi.adoc#persistent-storage-using-csi[Persistent storage using the Container Storage Interface (CSI)].
   
  
positive.code: 
  To install {product-title} 3.11, you prepared your {op-system-base-full} hosts, set all of the configuration values your cluster needed, and then ran an Ansible playbook to install and set up your cluster.
  
  In {product-title} 4.4, you use the OpenShift installation program to create a minimum set of resources required for a cluster. Once the cluster is running, you use Operators to further configure your cluster and to install new services. After first boot, {op-system-first} systems are managed by the Machine Config Operator (MCO) that runs in the {product-title} cluster.
  
  For more information, see xref:../../architecture/architecture-installation.adoc#installation-process_architecture-installation[Installation process].
  
  ifndef::openshift-origin[]
  If you want to add RHEL worker machines to your {product-title} 4.4 cluster, you use an Ansible playbook to join the RHEL worker machines after the cluster is running. For more information, see xref:../../machine_management/adding-rhel-compute.adoc#adding-rhel-compute[Adding RHEL compute machines to an {product-title} cluster].
  endif::[]
  
  [discrete]
  
negative.code: [discrete]
  ==== Unsupported persistent storage options
  
  Support for the following persistent storage options from {product-title} 3.11 has changed in {product-title} 4.5:
  
  * GlusterFS is no longer supported.
  * CephFS as a standalone product is no longer supported.
  * Ceph RBD as a standalone product is no longer supported.
  
  If you used of one these in {product-title} 3.11, you must choose a different persistent storage option for full support in {product-title} 4.5.
  
  For more information, see xref:../../storage/understanding-persistent-storage.adoc#understanding-persistent-storage[Understanding persistent storage].
  
  [id="migration-preparing-networking"]
  === Networking considerations
  
  Review the following networking changes to consider when transitioning from {product-title} 3.11 to {product-title} 4.5.
  
  [discrete]
  ==== Network isolation mode
  
  The default network isolation mode for {product-title} 3.11 was `ovs-subnet`, though users frequently switched to use `ovn-multitenant`. The default network isolation mode for {product-title} 4.5 is now NetworkPolicy.
  
  If your {product-title} 3.11 cluster used the `ovs-subnet` or `ovs-multitenant` mode, it is recommended to switch to the NetworkPolicy mode for your {product-title} 4.5 cluster. NetworkPolicy is supported upstream, is more flexible, and also provides the functionality that `ovs-multitenant` does. If you want to maintain the `ovs-multitenant` behavior while using NetworkPolicy in {product-title} 4.5, follow the steps to xref:../../networking/configuring-networkpolicy.adoc#nw-networkpolicy-multitenant-isolation_configuring-networkpolicy-plugin[configure multitenant isolation using NetworkPolicy].
  
  For more information, see xref:../../networking/configuring-networkpolicy.adoc#nw-networkpolicy-about_configuring-networkpolicy-plugin[About network policy].
  
  [discrete]
  ==== Encrypting traffic between hosts
  
  In {product-title} 3.11, you could use IPsec to encrypt traffic between hosts. {product-title} 4.5 does not support IPsec. It is recommended to use Red Hat OpenShift Service Mesh to enable mutual TLS between services.
  
  ifndef::openshift-origin[]
  For more information, see xref:../../service_mesh/service_mesh_arch/understanding-ossm.adoc#understanding-ossm[Understanding Red Hat OpenShift Service Mesh].
  