diff --git a/capibara.nix b/capibara.nix
index 751e2c0..d86884f 100644
--- a/capibara.nix
+++ b/capibara.nix
@@ -122,6 +122,23 @@ in {
   #  };
   #};
 
+  # todo: target and/or archive
+  services.btrbk.instances.btrbk = {
+    onCalendar = "*:0/30"; # every 30 minutes
+    settings = {
+      snapshot_preserve = "2d";
+      snapshot_preserve_min = "latest";
+      snapshot_create = "onchange";
+      volume."/mnt/btr_root" = {
+        snapshot_dir = "btrbk_snapshots";
+        subvolume = {
+          data = { };
+          persist = { };
+        };
+      };
+    };
+  };
+
   services.xserver.deviceSection = ''
     Option "TearFree" "true"
   '';
diff --git a/trantor.nix b/trantor.nix
index 8cd1453..42c66d8 100644
--- a/trantor.nix
+++ b/trantor.nix
@@ -163,6 +163,23 @@ in {
   #   };
   # };
 
+  # todo: target and/or archive
+  services.btrbk.instances.btrbk = {
+    onCalendar = "*:0/30"; # every 30 minutes
+    settings = {
+      snapshot_preserve = "2d";
+      snapshot_preserve_min = "latest";
+      snapshot_create = "onchange";
+      volume."/mnt/btr_user" = {
+        snapshot_dir = "btrbk_snapshots";
+        subvolume = {
+          data = { };
+          persist = { };
+        };
+      };
+    };
+  };
+
   networking = {
     hostName = "trantor";
     interfaces = {