diff --git a/hosts/hastur/spec.nix b/hosts/hastur/spec.nix
index b608d459f..33746591e 100644
--- a/hosts/hastur/spec.nix
+++ b/hosts/hastur/spec.nix
@@ -99,6 +99,21 @@
         # xserver.enable = true;
         # xserver.displayManager.gdm.enable = true;
         # xserver.desktopManager.gnome.enable = true;
+        snapy.instances = [
+          {
+            name = "persist";
+            source = "/persist";
+            keep = "2hr";
+            calendar = "*:0/3";
+          }
+          {
+            name = "var";
+            source = "/var";
+            keep = "2hr";
+            calendar = "*:0/3";
+          }
+        ];
+
         tailscale = { enable = true; openFirewall = true; };
 
         dae.enable = true;
diff --git a/modules/snapy.nix b/modules/snapy.nix
index e716851f6..214f428eb 100644
--- a/modules/snapy.nix
+++ b/modules/snapy.nix
@@ -23,7 +23,7 @@ in
           };
           keep = mkOption {
             type = types.str;
-            default = "3day";
+            default = "3hr";
           };
         };
       });
@@ -55,7 +55,6 @@ in
               description = "${s.name} snapy daemon";
               serviceConfig =
                 {
-                  # DynamicUser = true;
                   User = "root";
                   ExecStart =
                     let btrfs = lib.getExe' pkgs.btrfs-progs "btrfs"; in
@@ -63,17 +62,15 @@ in
                       {
                         name = "snapy";
                         script = ''
+                          let date_format = "%Y-%m-%d_%H:%M:%S%z"
+
                           # take snapshot
-                          date now | format date "%m-%d_%H:%M:%S" | ${btrfs} subvol snapshot -r ${s.source} $'${s.source}/.snapshots/($in)'
+                          date now | format date $date_format | ${btrfs} subvol snapshot -r ${s.source} $'${s.source}/.snapshots/($in)'
 
-                          date now
-                          # rm out-dated
-                          ls ${s.source}/.snapshots | filter { |i| ((date now) - $i.modified) > ${s.keep} } | each { |d| ${btrfs} sub del $d.name }
+                          # clean outdated
+                          ls ${s.source}/.snapshots | filter { |i| ((date now) - ($i.name | into datetime --format $date_format)) > ${s.keep} } | each { |d| ${btrfs} sub del $d.name }
                         '';
                       }));
-
-                  # AmbientCapabilities = [ "CAP_SYS_ADMIN" "CAP_SYS_RESOURCE" "CAP_DAC_OVERRIDE" ];
-                  # CapabilityBoundingSet = [ "CAP_SYS_ADMIN" "CAP_SYS_RESOURCE" "CAP_DAC_OVERRIDE" ];
                 };
             };
           })