[mikester]

Wayne, what do you use to monitor response time to your websites from the Internet? In previous jobs I've used site monitoring tools like Gomez. Of course with these forums you really need to monitor query times - which I know you do...

I've never really noticed much slowness in recent weeks on your site myself but these types of problems are really f'ing hard to diagnose and troubleshoot. A lot of times it broke down to having to actually get the sniffer out and start looking for packets with long delta times between hosts to see which application was actually slowing down (to prove it's not the damn network).

For example, host A is a web server querying from TCP port 10801 to a SQL server on tcp port 1433 - the query gets there with only a 4ms travel time (fast, German made electrons) but then the SQL server sits on it (presumably looking up the data - slowly) and eventually responds 800ms later but the response packet only takes 4ms to get back from the SQL server to the web server. So that 800ms is the lag (these are made up numbers). that 800ms is what the customer will complain about - slow response time and it can be caused by many different things that AREN'T the network. Disk reads, busy disks, busy processors, running out of Ram and having to go to disk instead, poorly designed databases, etc...

Finally - the application developer sees that and says 'you mean it's not the network?'