nix-cache: Tweak settings

machines/nix-cache/configuration.nix

@@ -95,7 +95,7 @@
         listen = "127.0.0.1:8080";
 
         garbage-collection = {
-          default-retention-period = "3 months";
+          default-retention-period = "6 weeks";
         };
 
         storage = {
@@ -116,16 +116,16 @@
           #
           # If 0, chunking is disabled entirely for newly-uploaded NARs.
           # If 1, all NARs are chunked.
-          nar-size-threshold = 64 * 1024; # 64 KiB
+          nar-size-threshold = 256 * 1024; # 256 KiB
 
           # The preferred minimum size of a chunk, in bytes
-          min-size = 16 * 1024; # 16 KiB
+          min-size = 128 * 1024; # 128 KiB
 
           # The preferred average size of a chunk, in bytes
-          avg-size = 64 * 1024; # 64 KiB
+          avg-size = 256 * 1024; # 256 KiB
 
           # The preferred maximum size of a chunk, in bytes
-          max-size = 256 * 1024; # 256 KiB
+          max-size = 1024 * 1024; # 1024 KiB
         };
       };
     };