A reminder to myself – there is a response header for SharePoint requests called the X-SharePointHealthScore. It indicates how stressed the server is with a score from zero (unstressed) to 10 (highly stressed). I first stumbled across it when debugging something in Fiddler, but others have written about it:
- Andrew Connell has a brief write up
- Mick Breeze dug into it with Reflector
- Michel Barneveld seems to have found it the same way as I did – but looks at how it is calculated. He also describes how to force SharePoint to return a given value, in case you need to test something (like how your client code handles a stressed server)
So how do we test the loadbalancer if we set it up in this fashion? Do we need to DDoS a WFE? There is a better way 😉 There is a registry setting that will override the Health Score and it will return the value from the registry.
Create a DWORD with the name ServerHealthScore in the following location: HKLMSOFTWAREMicrosoftShared ToolsWeb Server Extensions14.0WSS and give it the value you want.
So what’s it useful for? Well, the main things that strike me would be:
- Server Monitoring – Pretty obvious, really.
- Client Applications – Can warn or take corrective actions if the server is loaded and may implement throttling.
- Client Side scripts – Similar to above, though I haven’t yet been able to figure out who you’d get this value in the Client Object Model. I’m assuming there is a way to get the response headers in the Client Object Model – otherwise you may have to use normal XMLHttpRequests if you want to see the response headers.