Pin the fstrim timer and the monthly ZFS trim and scrub per host in the common role to keep them out of the backup window

common/defaults/main.yml

@@ -1 +1,8 @@
-ipv6_stable_secret: 1111:2222:3333:4444:5555:6666:7777:8888
+ipv6_stable_secret_seed: "@JW7rQ^P3*f^KRkX3744DZQJb3DfMgZJJMtGc!Jmy!ECBqb^QzAMYLHD8dLvf8m%2bRSRFhgY#SXzAgnxWTvHv#ti6b5PngR^k2gHbQW*%dJ9sdeKM$H77Gymh&xamNN"
+
+# Times of the heavy disk jobs, for hosts on a shared HDD pool that keep them out of the backup window.
+disk_maintenance:
+  # systemd OnCalendar for fstrim.timer; unset keeps the distribution schedule.
+  fstrim_on_calendar:
+  # Cron "minute hour" of the monthly ZFS trim and scrub from zfsutils-linux; unset keeps 00:24.
+  zfs_cron_time:

common/tasks/disk_maintenance.yml

@@ -0,0 +1,35 @@
+- name: Pin the fstrim timer
+  when: disk_maintenance.fstrim_on_calendar | default(none) is not none
+  block:
+    - name: Create the fstrim timer drop-in directory
+      file:
+        path: /etc/systemd/system/fstrim.timer.d
+        state: directory
+
+    - name: Set the fstrim timer schedule
+      copy:
+        dest: /etc/systemd/system/fstrim.timer.d/schedule.conf
+        content: |
+          [Timer]
+          OnCalendar=
+          OnCalendar={{ disk_maintenance.fstrim_on_calendar }}
+          RandomizedDelaySec=0
+          # A catch-up run after a boot or a timezone change would land at any time.
+          Persistent=false
+      register: fstrim_timer
+
+    - name: Restart the fstrim timer
+      when: fstrim_timer.changed
+      systemd:
+        name: fstrim.timer
+        daemon_reload: yes
+        state: restarted
+
+- name: Schedule the monthly ZFS trim and scrub
+  when: disk_maintenance.zfs_cron_time | default(none) is not none
+  lineinfile:
+    path: /etc/cron.d/zfsutils-linux
+    regexp: '^\S+ \S+ (\S+ \* \* root .*/usr/lib/zfs-linux/{{ item }};.*)$'
+    line: '{{ disk_maintenance.zfs_cron_time }} \1'
+    backrefs: yes
+  loop: [trim, scrub]

common/tasks/main.yml

@@ -9,3 +9,5 @@
 - import_tasks: ./aliases.yml
 
 - import_tasks: ./networking.yml
+
+- import_tasks: ./disk_maintenance.yml