Detail on changing primary storage scope added to adminguide and concepts (#395)

* Details about changing primary storage scope added to adminguide and conceptsandterminology

* Pull 395: Added screenshot for cluster to zone scope change

* Pull 395: Updated screenshot for cluster to zone scope change

* Pull 395: updated image after change in dialog

* Pull 395: simplified hypervisor-storage combinations

* Pull 395: Added info that this might be a long running operation

* Pull 395: Added info about listAffectedVmsForstorageScopeChange api

Author: abh1sar

source/_static/images/change-storage-pool-scope-to-zone.png

@@ -185,6 +185,42 @@ ensure that the protocol is set to "Filesystem".
 
 |adding-local-pool-via-ui.png|
 
+Changing the Scope of the Primary Storage
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Scope of a Primary Storage can be changed from Zone-wide to Cluster-wide
+and vice versa when the Primary Storage is in Disabled state.
+An action button is displayed in UI for each Primary Storage in Disabled state.
+
+|change-storage-pool-scope-via-ui.png|
+
+Scope change from Cluster to Zone will connect the Primary Storage to all Hosts
+of the zone running the same hypervisor as set on the storage pool.
+
+|change-storage-pool-scope-to-zone.png|
+
+Scope change from Zone to Cluster will disconnect the Primary Storage from all
+Hosts that were previously connected to the Primary Storage and are not a part
+of the specified Cluster. So, if there are running VMs on such hosts using this
+Storage Pool, they cannot be disconnected from the hosts. In this case the Scope
+change operation will error out.
+The user VMs need to be stopped or migrated and system VMs need to be destroyed
+while the primary Storage is disabled, before attempting the operation again.
+listAffectedVmsForstorageScopeChange API can be used to get the list of all such VMs.
+
+This might be a long running operation depending on how many hosts are there
+in the zone which need to be connected or disconnected to the storage pool.
+
+This feature is tested and supported for the following hypervisor and storage
+combinations:
+
+-  KVM with NFS
+
+-  KVM wite CEPH/RBD
+
+-  VMWare with NFS
+
+It is possible to use this functionality with other configurations but some
+manual intervention might be needed by the Administrator to make it work.
 
 Storage Tags
 ~~~~~~~~~~~~
@@ -1483,6 +1519,10 @@ Deleting objects from a bucket
    :alt: Upload button
 .. |adding-local-pool-via-ui.png| image:: /_static/images/adding-local-pool-via-ui.png
    :alt: Adding Local Storage Pool via UI
+.. |change-storage-pool-scope-via-ui.png| image:: /_static/images/change-storage-pool-scope-via-ui.png
+   :alt: Change Primary Storage Scope via UI
+.. |change-storage-pool-scope-to-zone.png| image:: /_static/images/change-storage-pool-scope-to-zone.png
+   :alt: Change Primary Storage Scope to Zone via UI
 .. |list-unmanaged-managed-volumes.png| image:: /_static/images/list-unmanaged-managed-volumes.png
    :alt: List of Unmanaged and Managed Volumes
 .. |import-volume.png| image:: /_static/images/import-volume.png

source/_static/images/change-storage-pool-scope-via-ui.png

@@ -463,6 +463,25 @@ for example:
 If you intend to use only local disk for your installation, you can skip
 adding separate primary storage.
 
+Changing the Scope of the Primary Storage
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Starting 4.19.1.0, it is possible to change the Scope of a Primary Storage
+from Zone-wide to Cluster-wide and vice versa. The option will be visible only
+after the Primary Storage has been disabled.
+
+This feature is tested and supported for the following hypervisor and storage
+combinations:
+
+-  KVM with NFS
+
+-  KVM with CEPH/RBD
+
+-  VMWare with NFS
+
+It is possible to use this functionality with other configurations but some
+manual intervention might be needed by the Administrator to make it work.
+
 
 About Secondary Storage
 ~~~~~~~~~~~~~~~~~~~~~~~