diff --git a/group_vars/clients.yml.sample b/group_vars/clients.yml.sample
index 1bd4f6003..c2efad271 100644
--- a/group_vars/clients.yml.sample
+++ b/group_vars/clients.yml.sample
@@ -15,8 +15,8 @@ dummy:
 
 #user_config: false
 #pools:
-#  - { name: test, pgs: "{{ pool_default_pg_num }}" }
-#  - { name: test2, pgs: "{{ pool_default_pg_num }}" }
+#  - { name: test, pgs: "{{ ceph_conf_overrides.global.osd_pool_default_pg_num }}" }
+#  - { name: test2, pgs: "{{ ceph_conf_overrides.global.osd_pool_default_pg_num }}" }
 
 #keys:
 #  - { name: client.test, value: "mon 'allow r' osd 'allow class-read object_prefix rbd_children, allow rwx pool=test'" }
diff --git a/group_vars/mons.yml.sample b/group_vars/mons.yml.sample
index 844c6dff0..6470030f5 100644
--- a/group_vars/mons.yml.sample
+++ b/group_vars/mons.yml.sample
@@ -23,7 +23,6 @@ dummy:
 #cephx: true
 
 # CephFS
-#pool_default_pg_num: 128
 #cephfs_data: cephfs_data
 #cephfs_metadata: cephfs_metadata
 #cephfs: cephfs
@@ -50,16 +49,16 @@ dummy:
 #openstack_config: false
 #openstack_glance_pool:
 #  name: images
-#  pg_num: "{{ pool_default_pg_num }}"
+#  pg_num: "{{ osd_pool_default_pg_num }}"
 #openstack_cinder_pool:
 #  name: volumes
-#  pg_num: "{{ pool_default_pg_num }}"
+#  pg_num: "{{ osd_pool_default_pg_num }}"
 #openstack_nova_pool:
 #  name: vms
-#  pg_num: "{{ pool_default_pg_num }}"
+#  pg_num: "{{ osd_pool_default_pg_num }}"
 #openstack_cinder_backup_pool:
 #  name: backups
-#  pg_num: "{{ pool_default_pg_num }}"
+#  pg_num: "{{ osd_pool_default_pg_num }}"
 
 #openstack_pools:
 #  - "{{ openstack_glance_pool }}"
diff --git a/roles/ceph-client/defaults/main.yml b/roles/ceph-client/defaults/main.yml
index 4cc10939b..7ccffebc3 100644
--- a/roles/ceph-client/defaults/main.yml
+++ b/roles/ceph-client/defaults/main.yml
@@ -7,8 +7,8 @@ fetch_directory: fetch/
 
 user_config: false
 pools:
-  - { name: test, pgs: "{{ pool_default_pg_num }}" }
-  - { name: test2, pgs: "{{ pool_default_pg_num }}" }
+  - { name: test, pgs: "{{ ceph_conf_overrides.global.osd_pool_default_pg_num }}" }
+  - { name: test2, pgs: "{{ ceph_conf_overrides.global.osd_pool_default_pg_num }}" }
 
 keys:
   - { name: client.test, value: "mon 'allow r' osd 'allow class-read object_prefix rbd_children, allow rwx pool=test'" }
diff --git a/roles/ceph-client/tasks/main.yml b/roles/ceph-client/tasks/main.yml
index c2b363f62..b0ad7283d 100644
--- a/roles/ceph-client/tasks/main.yml
+++ b/roles/ceph-client/tasks/main.yml
@@ -1,4 +1,6 @@
 ---
 - include: pre_requisite.yml
 - include: create_users_keys.yml
-  when: user_config
+  when:
+    - user_config
+    - ceph_conf_overrides.global.osd_pool_default_pg_num is defined
diff --git a/roles/ceph-mon/defaults/main.yml b/roles/ceph-mon/defaults/main.yml
index d431e4310..cbe61432b 100644
--- a/roles/ceph-mon/defaults/main.yml
+++ b/roles/ceph-mon/defaults/main.yml
@@ -15,7 +15,6 @@ monitor_secret: "{{ monitor_keyring.stdout }}"
 cephx: true
 
 # CephFS
-pool_default_pg_num: 128
 cephfs_data: cephfs_data
 cephfs_metadata: cephfs_metadata
 cephfs: cephfs
@@ -42,16 +41,16 @@ calamari: false
 openstack_config: false
 openstack_glance_pool:
   name: images
-  pg_num: "{{ pool_default_pg_num }}"
+  pg_num: "{{ osd_pool_default_pg_num }}"
 openstack_cinder_pool:
   name: volumes
-  pg_num: "{{ pool_default_pg_num }}"
+  pg_num: "{{ osd_pool_default_pg_num }}"
 openstack_nova_pool:
   name: vms
-  pg_num: "{{ pool_default_pg_num }}"
+  pg_num: "{{ osd_pool_default_pg_num }}"
 openstack_cinder_backup_pool:
   name: backups
-  pg_num: "{{ pool_default_pg_num }}"
+  pg_num: "{{ osd_pool_default_pg_num }}"
 
 openstack_pools:
   - "{{ openstack_glance_pool }}"
diff --git a/roles/ceph-mon/tasks/ceph_keys.yml b/roles/ceph-mon/tasks/ceph_keys.yml
index 4aeb22923..5292180cc 100644
--- a/roles/ceph-mon/tasks/ceph_keys.yml
+++ b/roles/ceph-mon/tasks/ceph_keys.yml
@@ -30,6 +30,43 @@
     - cephx
     - groups[restapi_group_name] is defined
 
+# NOTE(leseb): we add a conditional for backward compatibility
+# so people that had 'pool_default_pg_num' declared will get
+# the same behaviour
+#
+- name: check if does global key exist in ceph_conf_overrides
+  set_fact:
+    global_in_ceph_conf_overrides: "{{ 'global' in ceph_conf_overrides }}"
+
+- name: check if ceph_conf_overrides.global.osd_pool_default_pg_num is set
+  set_fact:
+    osd_pool_default_pg_num_in_overrides: "{{ 'osd_pool_default_pg_num' in ceph_conf_overrides.global }}"
+  when: global_in_ceph_conf_overrides
+
+- name: get default value for osd_pool_default_pg_num
+  shell: |
+    ceph --cluster {{ cluster }} daemon mon.{{ monitor_name }} config get osd_pool_default_pg_num | grep -Po '(?<="osd_pool_default_pg_num": ")[^"]*'
+  failed_when: false
+  changed_when: false
+  run_once: true
+  register: default_pool_default_pg_num
+  when: (pool_default_pg_num is not defined or not global_in_ceph_conf_overrides)
+
+- set_fact:
+    osd_pool_default_pg_num: "{{ pool_default_pg_num }}"
+  when: pool_default_pg_num is defined
+
+- set_fact:
+    osd_pool_default_pg_num: "{{ default_pool_default_pg_num.stdout }}"
+  when:
+    - pool_default_pg_num is not defined
+    - default_pool_default_pg_num.rc == 0
+    - ceph_conf_overrides.global.osd_pool_default_pg_num is not defined
+
+- set_fact:
+    osd_pool_default_pg_num: "{{ ceph_conf_overrides.global.osd_pool_default_pg_num }}"
+  when: ceph_conf_overrides.global.osd_pool_default_pg_num is defined
+
 - include: rbd_pool.yml
   when: ceph_conf_overrides.global.osd_pool_default_pg_num is defined
 
diff --git a/roles/ceph-mon/tasks/create_mds_filesystems.yml b/roles/ceph-mon/tasks/create_mds_filesystems.yml
index e114b1511..f5103cbb9 100644
--- a/roles/ceph-mon/tasks/create_mds_filesystems.yml
+++ b/roles/ceph-mon/tasks/create_mds_filesystems.yml
@@ -4,7 +4,7 @@
 # the role 'ceph-common' doesn't get inherited so the condition can not be evaluate
 # since those check are performed by the ceph-common role
 - name: create filesystem pools
-  command: ceph --cluster {{ cluster }} osd pool create {{ item }} {{ pool_default_pg_num }}
+  command: ceph --cluster {{ cluster }} osd pool create {{ item }} {{ osd_pool_default_pg_num }}
   with_items:
     - cephfs_data
     - cephfs_metadata