Best way to handle a large download site?

Stream iStream = null;

// Buffer to read 10K bytes in chunk:
byte[] buffer = new Byte[10000];

// Length of the file:
int length;

// Total bytes to read:
long dataToRead;

if (File.Exists(localfilename))
{
    try
    {
        // Open the file.
        iStream = new System.IO.FileStream(localfilename, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read);

        // Total bytes to read:
        dataToRead = iStream.Length;

        context.Response.Clear();
        context.Response.Buffer = false;
        context.Response.ContentType = "application/octet-stream";
        Int64 fileLength = iStream.Length;
        context.Response.AddHeader("Content-Length", fileLength.ToString());
        context.Response.AddHeader("Content-Disposition", "attachment; filename=" + originalFilename);

        // Read the bytes.
        while (dataToRead > 0)
        {
            // Verify that the client is connected.
            if (context.Response.IsClientConnected)
            {
                // Read the data in buffer.
                length = iStream.Read(buffer, 0, 10000);

                // Write the data to the current output stream.
                context.Response.OutputStream.Write(buffer, 0, length);

                // Flush the data to the HTML output.
                context.Response.Flush();

                buffer = new Byte[10000];
                dataToRead = dataToRead - length;
            }
            else
            {
                //prevent infinite loop if user disconnects
                dataToRead = -1;
            }
        }
        iStream.Close();
        iStream.Dispose();
    }
    catch (Exception ex)
    {
        if (iStream != null)
        {
            iStream.Close();
            iStream.Dispose();
        }
        if (ex.Message.Contains("The remote host closed the connection"))
        {
            context.Server.ClearError();
            context.Trace.Warn("GetFile", "The remote host closed the connection");
        }
        else
        {
            context.Trace.Warn("IHttpHandler", "DownloadFile: - Error occurred");
            context.Trace.Warn("IHttpHandler", "DownloadFile: - Exception", ex);
        }
        context.Response.Redirect("default.aspx");
    }
}