Increase system stabillity by re-enabling swap and setting vm.swappiness to 10

roles/ceph-common/defaults/main.yml

@@ -365,12 +365,13 @@ ceph_conf_overrides: {}
 #############
 
 disable_transparent_hugepage: true
-disable_swap: true
+disable_swap: false
 os_tuning_params:
   - { name: kernel.pid_max, value: 4194303 }
   - { name: fs.file-max, value: 26234859 }
   - { name: vm.zone_reclaim_mode, value: 0 }
   - { name: vm.vfs_cache_pressure, value: 50 }
+  - { name: vm.swappiness, value: 10 }
   - { name: vm.min_free_kbytes, value: "{{ vm_min_free_kbytes }}" }