diff --git a/build_hm.sh b/build_hm.sh
index b675d9d..08a672b 100755
--- a/build_hm.sh
+++ b/build_hm.sh
@@ -17,7 +17,7 @@ function help {
     echo "  -h: Display this help message."
 }
 
-while getopts "hvb" OPTION
+while getopts "h" OPTION
 do
     case "$OPTION" in
         h)
diff --git a/curacao/backup/backup.sh b/curacao/backup/backup.sh
new file mode 100755
index 0000000..38448c2
--- /dev/null
+++ b/curacao/backup/backup.sh
@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+
+set -euxo pipefail
+
+# Parse arguments
+function help {
+    echo "Usage: $0 [-h|-i] volume"
+    echo "Backup BTRFS subvolume on rapido to razmo."
+    echo
+    echo "Arguments:"
+    echo "  volume: Name of the subvolume to backup"
+    echo
+    echo "Options:"
+    echo "  -h: Display this help message."
+    echo "  -i: Don't fail if the receiving subvolume doesn't exist."
+}
+
+init=false
+while getopts "hi" OPTION
+do
+    case "$OPTION" in
+        h)
+            help
+            exit 0
+            ;;
+        i)
+            init=true
+            ;;
+        ?)
+            help
+            exit 2
+            ;;
+    esac
+done
+shift "$((OPTIND - 1))"
+
+if [ "$#" -ne 1 ]
+then
+    help
+    exit 2
+fi
+volume="$1"
+
+# Assertions
+[ -d "/mnt/rapido/${volume}" ]
+[ -d "/mnt/rapido/${volume}.bkp" ] || "$init"
+[ ! -d "/mnt/rapido/${volume}.new" ]
+[ -d "/mnt/razmo/${volume}.bkp" ] || "$init"
+[ -d "/mnt/razmo/${volume}" ] || "$init"
+[ ! -d "/mnt/razmo/${volume}.new" ]
+[ ! -d "/mnt/razmo/${volume}.snapshots" ]
+
+# Taking a snapshot of the running subvolume
+btrfs subvolume snapshot -r "/mnt/rapido/${volume}" "/mnt/rapido/${volume}.new"
+
+# Sending (the difference with) the last backup to the backup disk
+function error_handler() {
+    btrfs subvolume delete "/mnt/rapido/${volume}.new" || true
+    btrfs subvolume delete "/mnt/razmo/${volume}.new" || true
+}
+trap error_handler ERR
+if [ -d "/mnt/rapido/${volume}.bkp" ]
+then
+    btrfs send -p "/mnt/rapido/${volume}.bkp" "/mnt/rapido/${volume}.new" | btrfs receive /mnt/razmo
+else
+    btrfs send "/mnt/rapido/${volume}.new" | btrfs receive /mnt/razmo
+fi
+trap - ERR
+
+# Removing old backups and putting the new one in place
+[ ! -d "/mnt/rapido/${volume}.bkp" ] || btrfs subvolume delete "/mnt/rapido/${volume}.bkp"
+mv "/mnt/rapido/${volume}.new" "/mnt/rapido/${volume}.bkp"
+[ ! -d "/mnt/razmo/${volume}.bkp" ] || btrfs subvolume delete "/mnt/razmo/${volume}.bkp"
+mv "/mnt/razmo/${volume}.new" "/mnt/razmo/${volume}.bkp"
+
+# Create a writeable clone in case we need to boot on the HDD
+# Needs to move away then back the .snapshots folder
+[ ! -d "/mnt/razmo/${volume}/.snapshots" ] || mv "/mnt/razmo/${volume}/.snapshots" "/mnt/razmo/${volume}.snapshots"
+[ ! -d "/mnt/razmo/${volume}" ] || btrfs subvolume delete "/mnt/razmo/${volume}"
+btrfs subvolume snapshot "/mnt/razmo/${volume}.bkp" "/mnt/razmo/${volume}"
+[ ! -d "/mnt/razmo/${volume}.snapshots" ] || mv "/mnt/razmo/${volume}.snapshots" "/mnt/razmo/${volume}/.snapshots"
+
+sync
diff --git a/curacao/backup/default.nix b/curacao/backup/default.nix
new file mode 100644
index 0000000..5041c60
--- /dev/null
+++ b/curacao/backup/default.nix
@@ -0,0 +1,64 @@
+{ pkgs, lib, ... }:
+# MANU Snapper is not able to create the snapshot directory, so you'll need to do this after eventually running the backup script:
+# sudo btrfs subvol create /mnt/razmo/$subvolume/.snapshots
+let
+  backup_subvolumes = [ "nixos" "home.rapido" ];
+  backup_app = pkgs.writeShellApplication {
+    name = "backup-subvolume";
+    runtimeInputs = with pkgs; [ coreutils btrfs-progs ];
+    text = builtins.readFile ./backup.sh;
+  };
+  snapper_subvolumes = [ "nixos" "home.rapido" "home.razmo" ];
+in
+{
+  services =
+    let
+      default = {
+        # filesystem type
+        FSTYPE = "btrfs";
+
+        # run daily number cleanup
+        NUMBER_CLEANUP = true;
+        NUMBER_MIN_AGE = 1800;
+        NUMBER_LIMIT = 25;
+
+        # create hourly snapshots
+        TIMELINE_CREATE = true;
+
+        # cleanup hourly snapshots after some time
+        TIMELINE_CLEANUP = true;
+        TIMELINE_MIN_AGE = 1800;
+        TIMELINE_LIMIT_HOURLY = 24;
+        TIMELINE_LIMIT_DAILY = 31;
+        TIMELINE_LIMIT_WEEKLY = 8;
+        TIMELINE_LIMIT_MONTHLY = 0;
+        TIMELINE_LIMIT_YEARLY = 0;
+
+        # cleanup empty pre-post-pairs
+        EMPTY_PRE_POST_CLEANUP = true;
+      };
+    in
+    {
+      snapper.configs = lib.attrsets.mergeAttrsList (map (s: { "${s}" = default // { SUBVOLUME = "/mnt/razmo/${s}"; }; }) snapper_subvolumes);
+    };
+
+
+  systemd = {
+    services.bkp_rapido = {
+      description = "Make a snapshot of the SSD to the HDD";
+      before = [ "snapper-timeline.service" ];
+      serviceConfig = {
+        Type = "oneshot";
+        ExecStart = map (s: "${backup_app}/bin/backup-subvolume ${s}") backup_subvolumes;
+      };
+      # TODO Harden
+    };
+    timers.bkp_rapido = {
+      description = "Regular snapshot of SSD to HDD";
+      timerConfig = {
+        OnCalendar = "hourly";
+      };
+      wantedBy = [ "timers.target" ];
+    };
+  };
+}
diff --git a/curacao/dk.nix b/curacao/dk.nix
index fa2660b..62323c8 100644
--- a/curacao/dk.nix
+++ b/curacao/dk.nix
@@ -1,5 +1,4 @@
 { passwordFile ? "/should_not_be_needed_in_this_context", ... }:
-# FIXME Subvolumes for backup. If they're not created with the script. Add the script btw.
 # TODO Not relatime everywhere, thank you
 # TODO Default options
 let
diff --git a/curacao/os.nix b/curacao/os.nix
index b92c72c..9e9d2ea 100644
--- a/curacao/os.nix
+++ b/curacao/os.nix
@@ -5,6 +5,7 @@
     ./options.nix
     ./hardware.nix
     ./dk.nix
+    ./backup
   ];
 
   networking.hostName = "curacao";