Use a lower file size target (10MB instead of 100MB) when using archive V2, as the average block size is over 90% smaller.

src/main/java/org/qortal/repository/BlockArchiveWriter.java

@@ -39,7 +39,8 @@ public class BlockArchiveWriter {
 
     private static final Logger LOGGER = LogManager.getLogger(BlockArchiveWriter.class);
 
-    public static final long DEFAULT_FILE_SIZE_TARGET = 100 * 1024 * 1024; // 100MiB
+    public static final long DEFAULT_FILE_SIZE_TARGET_V1 = 100 * 1024 * 1024; // 100MiB
+    public static final long DEFAULT_FILE_SIZE_TARGET_V2 = 10 * 1024 * 1024; // 10MiB
 
     private int startHeight;
     private final int endHeight;
@@ -47,7 +48,7 @@ public class BlockArchiveWriter {
     private final Path archivePath;
     private final Repository repository;
 
-    private long fileSizeTarget = DEFAULT_FILE_SIZE_TARGET;
+    private long fileSizeTarget = DEFAULT_FILE_SIZE_TARGET_V1;
     private boolean shouldEnforceFileSizeTarget = true;
 
     // Default data source to BLOCK_REPOSITORY; can optionally be overridden
@@ -75,6 +76,12 @@ public class BlockArchiveWriter {
             // When serialization version isn't specified, fetch it from the existing archive
             serializationVersion = this.findSerializationVersion();
         }
+
+        // Reduce default file size target if we're using V2, as the average block size is over 90% smaller
+        if (serializationVersion == 2) {
+            this.setFileSizeTarget(DEFAULT_FILE_SIZE_TARGET_V2);
+        }
+
         this.serializationVersion = serializationVersion;
     }