Asp.net accumulate and write TXT files

String m_logname = server. mappath ("logserver.txt ");
If (! System. Io. file. exists (m_logname ))
{

System. Io. filestream fsnew = system. Io. file. Create (m_logname );
Fsnew. Close ();
}
Using (system. Io. filestream FS = system. Io. file. Open (m_logname, system. Io. filemode. append, system. Io. fileaccess. Write ))
{
Using (system. Io. streamwriter W = new system. Io. streamwriter (FS ))
{
W. writeline ("record time: {0}", datetime. Now. tostring ());
W. writeline ("User ID: {0}", "11 ");
W. writeline ("User name: {0}", "22 ");
W. writeline ("IP Address: {0}", request. userhostaddress );
W. writeline ("MAC address: {0}", getcustomermac (request. userhostaddress ));
W. writeline ("Upload File Path: {0}", request. url. tostring ());
W. writeline ("succeeded ("---------------------------------------------------------------------------------------------");
W. Flush ();
W. Close ();
}
}