Locked File on Web Farm

Hi,

I'm creating a thread safe TextWriter like this...

TextWriter sw = TextWriter.Synchronized(File.AppendText(ConfigurationManager.AppSettings["logfilePath"]));
xtw = new XmlTextWriter(sw);
 
If this code is part of a web site that's running on a web farm, what exactly happens? Are there multiple copies of the file? If so, how does the system keep them in sync?

Cheers, WT.
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