The speed of writting big files depends on the client speed if you have slow clients and want to send 50 mb you probably need to go to asynch solution or write the file and get it served by the default servlet (use native or NIO2 connector to get native sendfile).
If you want use sendFile() look to the DefaultServlet code.
Thank u for Reply..
what is the meaning of 'native or NIO2 connector to get native sendfile'?
In org.apache.catalina.servlets.DefaultServlet code doesn't contain sendFile().