New system property "h2.syncMethod".

h2/src/main/org/h2/constant/SysProperties.java

@@ -536,6 +536,18 @@ public class SysProperties {
      */
     public static final long SPLIT_FILE_SIZE_SHIFT = getIntSetting("h2.splitFileSizeShift", 30);
 
+    /**
+     * System property <code>h2.syncMethod</code> (default: sync).<br />
+     * What method to call when closing the database, on checkpoint, and on
+     * CHECKPOINT SYNC. The following options are supported:
+     * "sync" (default): RandomAccessFile.getFD().sync();
+     * "force": RandomAccessFile.getChannel().force(true);
+     * "forceFalse": RandomAccessFile.getChannel().force(false);
+     * "": do not call a method (fast but there is a risk of data loss
+     * on power failure).
+     */
+    public static final String SYNC_METHOD = getStringSetting("h2.syncMethod", "sync");
+
     /**
      * System property <code>h2.traceIO</code> (default: false).<br />
      * Trace all I/O operations.

h2/src/main/org/h2/store/fs/FileObjectDisk.java

@@ -10,6 +10,7 @@ import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 
+import org.h2.constant.SysProperties;
 import org.h2.util.IOUtils;
 
 /**
@@ -25,7 +26,18 @@ public class FileObjectDisk extends RandomAccessFile implements FileObject {
     }
 
     public void sync() throws IOException {
-        getFD().sync();
+        String m = SysProperties.SYNC_METHOD;
+        if ("".equals(m)) {
+            // do nothing
+        } else if ("sync".equals(m)) {
+            getFD().sync();
+        } else if ("force".equals(m)) {
+            getChannel().force(true);
+        } else if ("forceFalse".equals(m)) {
+            getChannel().force(false);
+        } else {
+            getFD().sync();
+        }
     }
 
     public void setFileLength(long newLength) throws IOException {