Increase disk requirement and node limit (#108)

* Increase disk requirement
* Increase max number of cluster nodes

cluster.rst

@@ -4,14 +4,28 @@
 Cluster management
 ==================
 
-A NethServer 8 `cluster <https://en.wikipedia.org/wiki/Computer_cluster>`_ is composed of one **leader** node
-and multiple **worker** nodes.
+A NethServer 8 cluster_ is composed of one **leader** node and multiple
+**worker** nodes.
 
-An NS8 cluster composed only of the leader node, is a fully functional system.
-Worker nodes can be added or removed at any time.
-NS8 clusters support a maximum of 4 nodes.
+.. _cluster: https://en.wikipedia.org/wiki/Computer_cluster
+
+All nodes are managed through the Web user interface, which operates on
+the leader node.
+
+An NS8 cluster consisting solely of the leader node is a fully functional
+system. Worker nodes can be added or removed at any time.
+
+The VPN network chosen during the initial leader node setup determines the
+limit on the number of possible cluster nodes. Note that a node's VPN IP
+is never released once allocated: removing a node does not free its VPN IP
+address.
+
+The default VPN network ``10.5.4.0/24`` supports up to 254 cluster nodes.
+
+In theory, the maximum number of nodes in an NS8 cluster is limited only
+by the VPN network size. However, it is advisable to add nodes gradually
+to avoid degrading the leader's performance due to increasing workload.
 
-All nodes are managed by the Web user interface running on the leader node.
 
 Add a node
 ==========

install.rst

@@ -99,16 +99,16 @@ executing: ::
 Post-installation steps
 =======================
 
-When the installation script ends or the pre-built image has started,
-access the Web user interface at ::
+When the installation script completes or the pre-built image has started,
+access the Web user interface at: ::
 
     https://<server_ip_or_fqdn>/cluster-admin/
 
 .. hint::
 
-   If the node is unreachable see :ref:`os-network-section`
+   If the node is unreachable, refer to :ref:`os-network-section`.
 
-The default credentials to login on cluster-admin are
+The default credentials for logging in to the cluster-admin interface are:
 
 * Username: ``admin``
 * Password: ``Nethesis,1234``
@@ -118,32 +118,37 @@ single-node cluster. Alternatively, you can join the node to an existing
 cluster as described in :ref:`cluster-section`, or restore a cluster
 backup as detailed in :ref:`disaster_recovery-section`.
 
-For security reasons, the admin password must be changed immediately if it
-is still at the default value.
+For security reasons, change the admin password immediately if it is still
+set to the default value.
 
-Ensure the node Fully Qualified Domain Name (FQDN) is correct, and
-respects the :ref:`DNS requirements <dns-reqs>`.
+Ensure the node's Fully Qualified Domain Name (FQDN) is correct and meets
+the :ref:`DNS requirements <dns-reqs>`.
 
-Even if running on a single node, the system will setup a Virtual Private
-Network (VPN) for the cluster. With the VPN in place, you will be able to
-add more nodes in the future. The proposed default values should be good
-for most environments, anyway make sure ``VPN network (CIDR)`` does not
-conflict with your existing network environment, because it cannot be
-changed once it has been set.
+Even if running on a single node, the system will set up a Virtual Private
+Network (VPN) for the cluster. This VPN setup will allow you to add more
+nodes in the future. The proposed default values should be suitable for most
+environments, as it theoretically accommodates up to 254 cluster nodes.
+However, ensure that the ``VPN network (CIDR)`` does not conflict with your
+existing network environment, as it cannot be changed once set.
 
-Finally, click on :guilabel:`Create cluster` button. Your NS8 is now ready.
+Finally, click the :guilabel:`Create cluster` button. Your NS8 is now
+ready.
 
-A new cluster has assigned the default name ``NethServer 8``. If you wish to
+By default, the new cluster is named ``NethServer 8``. If you wish to
 change it:
 
-* go to the ``Settings`` page and click on the ``Cluster`` card
-* enter a name inside the ``Cluster label`` field
-* click the :guilabel:`Save settings` button
+* Go to the ``Settings`` page and click on the ``Cluster`` card.
+* Enter a new name in the ``Cluster label`` field.
+* Click the :guilabel:`Save settings` button.
 
-Now sure where to go from here?
-You can install a :ref:`LDAP <openldap-section>` or :ref:`Active Directory <active_directory-section>` user domain,
-read an introduction about :ref:`modules <modules-section>`,
-take a look at :ref:`system logs <loki-section>`, add :ref:`new nodes <cluster-section>`, or setup a :ref:`metric dashboard <metrics-section>`.
+Not sure where to go from here? You can:
+
+* Install an :ref:`LDAP <openldap-section>` or :ref:`Active Directory
+  <active_directory-section>` user domain.
+* Read an introduction about :ref:`NS8 applications <modules-section>`.
+* Take a look at :ref:`system logs <loki-section>`.
+* Add :ref:`new nodes <cluster-section>`.
+* Set up a :ref:`metric dashboard <metrics-section>`.
 
 Uninstall
 =========

system_requirements.rst

@@ -11,7 +11,7 @@ Minimum hardware requirements for a single node installation:
 
 - 2 vCPU/cores, x86-64 architecture
 - 2GB RAM
-- 20GB disk
+- 40GB Solid-state drive
 
 More nodes can be added later, and when adding a new node, it is
 recommended to use similar hardware and the same Linux distribution