Vincent wrote:
  BTW if you have setup some tools and have had
successes
 with them to monitor xwiki instances, it would be great if
 you could add some doc about them at 
 
http://platform.xwiki.org/xwiki/bin/view/AdminGuide/Monitoring
  
Thanks for the pointers. These sound like useful tools, although I think to cover the
situation I encountered (web services looked up) I probably need to get more familiar with
the logs, make sure they collect the right stuff, and have a command-line tool to filter
it. But yes, I shall certainly contribute any experience I glean back into the wiki.